scholarly journals Susceptibility of Cryptococcus neoformans to Photodynamic Inactivation Is Associated with Cell Wall Integrity

2007 ◽  
Vol 51 (8) ◽  
pp. 2929-2936 ◽  
Author(s):  
Beth Burgwyn Fuchs ◽  
George P. Tegos ◽  
Michael R. Hamblin ◽  
Eleftherios Mylonakis
Keyword(s):  
Cell Wall ◽  
Photodynamic Therapy ◽  
Cryptococcus Neoformans ◽  
Cell Wall Integrity ◽  
Photodynamic Inactivation ◽  
Nucleotide Exchange ◽  
Wild Type ◽  
Kinase C ◽  
Nucleotide Exchange Factor ◽  
Cell Wall Integrity Pathway

ABSTRACT Photodynamic therapy is a rapidly developing antimicrobial technology which combines a nontoxic photoactivatable dye or photosensitizer with harmless visible light of the correct wavelength to excite the dye to its reactive triplet state to generate reactive oxygen species toxic to cells. In this report we present evidence that the fungal pathogen Cryptococcus neoformans is susceptible to photodynamic inactivation by use of a polycationic conjugate of polyethyleneimine and the photosensitizer chlorin(e6). A C. neoformans rom2 mutant, with a mutation involving a putative Rho1 guanyl nucleotide exchange factor that is part of the protein kinase C-cell wall integrity pathway, demonstrated a compromised cell wall and less (1,3)β-d glucan than the wild-type strain and increased accumulation of PEI-ce6 as assessed by fluorescence uptake and confocal microscopy. Interestingly, C. neoformans rom2 was hypersusceptible to photodynamic inactivation and coincubation of wild-type C. neoformans strain KN99α with caspofungin-enhanced photoinactivation. These studies demonstrated that C. neoformans is sensitive to photodynamic therapy and illustrated the significance of cell wall integrity in microbial susceptibility to antimicrobial photodynamic inactivation.

scholarly journals Cross Talk between the Cell Wall Integrity and Cyclic AMP/Protein Kinase A Pathways in Cryptococcus neoformans

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Maureen J. Donlin ◽  
Rajendra Upadhya ◽  
Kimberly J. Gerik ◽  
Woei Lam ◽  
Laura G. VanArendonk ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Cryptococcus Neoformans ◽  
Signaling Pathway ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Content Type ◽  
Kinase A

ABSTRACTCryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely,PKC1,BCK1,MKK2, andMPK1results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions ofBCK1,MKK2, andMPK1compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis.IMPORTANCECryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.

scholarly journals PRO40 Is a Scaffold Protein of the Cell Wall Integrity Pathway, Linking the MAP Kinase Module to the Upstream Activator Protein Kinase C

PLoS Genetics ◽  
2014 ◽  
Vol 10 (9) ◽  
pp. e1004582 ◽  
Author(s):  
Ines Teichert ◽  
Eva Katharina Steffens ◽  
Nicole Schnaß ◽  
Benjamin Fränzel ◽  
Christoph Krisp ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Map Kinase ◽  
Scaffold Protein ◽  
Cell Wall Integrity ◽  
Activator Protein ◽  
Kinase C ◽  
Cell Wall Integrity Pathway

scholarly journals Role of the Guanine Nucleotide Exchange Factor Rom2 in Cell Wall Integrity Maintenance of Aspergillus fumigatus

2012 ◽  
Vol 12 (2) ◽  
pp. 288-298 ◽  
Author(s):  
Sweta Samantaray ◽  
Michael Neubauer ◽  
Christoph Helmschrott ◽  
Johannes Wagener
Keyword(s):  
Cell Wall ◽  
Aspergillus Fumigatus ◽  
Guanine Nucleotide Exchange Factor ◽  
Cell Wall Integrity ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Content Type ◽  
Guanine Nucleotide Exchange ◽  
Stress Sensors ◽  
Nucleotide Exchange Factor

ABSTRACTAspergillus fumigatusis a mold and the causal agent of invasive aspergillosis, a systemic disease with high lethality. Recently, we identified and functionally characterized three stress sensors implicated in the cell wall integrity (CWI) signaling of this pathogen, namely, Wsc1, Wsc3, and MidA. Here, we functionally characterize Rom2, a guanine nucleotide exchange factor with essential function for the cell wall integrity ofA. fumigatus. A conditionalrom2mutant has severe growth defects under repressive conditions and incorporates all phenotypes of the three cell wall integrity sensor mutants, e.g., the echinocandin sensitivity of the Δwsc1mutant and the Congo red, calcofluor white, and heat sensitivity of the ΔmidAmutant. Rom2 interacts with Rho1 and shows a similar intracellular distribution focused at the hyphal tips. Our results place Rom2 between the cell surface stress sensors Wsc1, Wsc3, MidA, and Rho1 and their downstream effector mitogen-activated protein (MAP) kinase module Bck1-Mkk2-MpkA.

scholarly journals Cell Wall Integrity Pathway Involved in Morphogenesis, Virulence and Antifungal Susceptibility in Cryptococcus neoformans

2021 ◽  
Vol 7 (10) ◽  
pp. 831
Author(s):  
Haroldo Cesar de Oliveira ◽  
Suelen Andreia Rossi ◽  
Irene García-Barbazán ◽  
Óscar Zaragoza ◽  
Nuria Trevijano-Contador
Keyword(s):  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Morphological Changes ◽  
Antifungal Susceptibility ◽  
Pathogenic Fungi ◽  
Cell Wall Integrity ◽  
Cell Permeability ◽  
Fungal Cell ◽  
Cell Wall Integrity Pathway ◽  
Fungal Kingdom

Due to its location, the fungal cell wall is the compartment that allows the interaction with the environment and/or the host, playing an important role during infection as well as in different biological functions such as cell morphology, cell permeability and protection against stress. All these processes involve the activation of signaling pathways within the cell. The cell wall integrity (CWI) pathway is the main route responsible for maintaining the functionality and proper structure of the cell wall. This pathway is highly conserved in the fungal kingdom and has been extensively characterized in Saccharomyces cerevisiae. However, there are still many unknown aspects of this pathway in the pathogenic fungi, such as Cryptococcus neoformans. This yeast is of particular interest because it is found in the environment, but can also behave as pathogen in multiple organisms, including vertebrates and invertebrates, so it has to adapt to multiple factors to survive in multiple niches. In this review, we summarize the components of the CWI pathway in C. neoformans as well as its involvement in different aspects such as virulence factors, morphological changes, and its role as target for antifungal therapies among others.

scholarly journals Wsc1 and Mid2 Are Cell Surface Sensors for Cell Wall Integrity Signaling That Act through Rom2, a Guanine Nucleotide Exchange Factor for Rho1

2001 ◽  
Vol 21 (1) ◽  
pp. 271-280 ◽  
Author(s):  
Bevin Philip ◽  
David E. Levin
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Cell Surface ◽  
G Protein ◽  
Guanine Nucleotide Exchange Factor ◽  
Cell Wall Integrity ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor

ABSTRACT Wsc1 and Mid2 are highly O-glycosylated cell surface proteins that reside in the plasma membrane of Saccharomyces cerevisiae. They have been proposed to function as mechanosensors of cell wall stress induced by wall remodeling during vegetative growth and pheromone-induced morphogenesis. These proteins are required for activation of the cell wall integrity signaling pathway that consists of the small G-protein Rho1, protein kinase C (Pkc1), and a mitogen-activated protein kinase cascade. We show here by two-hybrid experiments that the C-terminal cytoplasmic domains of Wsc1 and Mid2 interact with Rom2, a guanine nucleotide exchange factor (GEF) for Rho1. At least with regard to Wsc1, this interaction is mediated by the Rom2 N-terminal domain. This domain is distinct from the Rho1-interacting domain, suggesting that the GEF can interact simultaneously with a sensor and with Rho1. We also demonstrate that extracts from wsc1 and mid2 mutants are deficient in the ability to catalyze GTP loading of Rho1 in vitro, providing evidence that the function of the sensor-Rom2 interaction is to stimulate nucleotide exchange toward this G-protein. In a related line of investigation, we identified the PMT2 gene in a genetic screen for mutations that confer an additive cell lysis defect with a wsc1 null allele. Pmt2 is a member of a six-protein family in yeast that catalyzes the first step in O mannosylation of target proteins. We demonstrate that Mid2 is not mannosylated in apmt2 mutant and that this modification is important for signaling by Mid2.

scholarly journals Receptor Internalization in Yeast Requires the Tor2-Rho1 Signaling Pathway

2003 ◽  
Vol 14 (11) ◽  
pp. 4676-4684 ◽  
Author(s):  
Amy K.A. deHart ◽  
Joshua D. Schnell ◽  
Damian A. Allen ◽  
Ju-Yun Tsai ◽  
Linda Hicke
Keyword(s):  
Cell Wall ◽  
Cell Cycle Progression ◽  
Structural Integrity ◽  
Nutrient Sensing ◽  
Receptor Internalization ◽  
Cell Integrity ◽  
Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Similar Phenotype ◽  
Cell Growth And Differentiation

Efficient internalization of proteins from the cell surface is essential for regulating cell growth and differentiation. In a screen for yeast mutants defective in ligand-stimulated internalization of the α-factor receptor, we identified a mutant allele of TOR2, tor2G2128R. Tor proteins are known to function in translation initiation and nutrient sensing and are required for cell cycle progression through G1. Yeast Tor2 has an additional role in regulating the integrity of the cell wall by activating the Rho1 guanine nucleotide exchange factor Rom2. The endocytic defect in tor2G2128Rcells is due to disruption of this Tor2 unique function. Other proteins important for cell integrity, Rom2 and the cell integrity sensor Wsc1, are also required for efficient endocytosis. A rho1 mutant specifically defective in activation of the glucan synthase Fks1/2 does not internalize α-factor efficiently, and fks1Δ cells exhibit a similar phenotype. Removal of the cell wall does not inhibit internalization, suggesting that the function of Rho1 and Fks1 in endocytosis is not through cell wall synthesis or structural integrity. These findings reveal a novel function for the Tor2-Rho1 pathway in controlling endocytosis in yeast, a function that is mediated in part through the plasma membrane protein Fks1.

Pneumocystis carinii BCK1 Complements the Saccharomyces cerevisiae Cell Wall Integrity Pathway

2003 ◽  
Vol 50 (s1) ◽  
pp. 676-677 ◽  
Author(s):  
PAWAN K. VOHRA ◽  
THEODORE J. KOTTOM ◽  
ANDREW H. LIMPER ◽  
CHARLES F. THOMAS
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Pneumocystis Carinii ◽  
Cell Wall Integrity ◽  
Cell Wall Integrity Pathway

scholarly journals Aspergillus nidulans Protein O-Mannosyltransferases Play Roles in Cell Wall Integrity and Developmental Patterning

2009 ◽  
Vol 8 (10) ◽  
pp. 1475-1485 ◽  
Author(s):  
Thanyanuch Kriangkripipat ◽  
Michelle Momany
Keyword(s):  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Double Mutant ◽  
Elevated Temperatures ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Spatial Cues ◽  
Developmental Patterning ◽  
In The Wild ◽  
Increased Sensitivity

ABSTRACT Protein O-mannosyltransferases (Pmts) initiate O-mannosyl glycan biosynthesis from Ser and Thr residues of target proteins. Fungal Pmts are divided into three subfamilies, Pmt1, -2, and -4. Aspergillus nidulans possesses a single representative of each Pmt subfamily, pmtA (subfamily 2), pmtB (subfamily 1), and pmtC (subfamily 4). In this work, we show that single Δpmt mutants are viable and have unique phenotypes and that the ΔpmtA ΔpmtB double mutant is the only viable double mutant. This makes A. nidulans the first fungus in which all members of individual Pmt subfamilies can be deleted without loss of viability. At elevated temperatures, all A. nidulans Δpmt mutants show cell wall-associated defects and increased sensitivity to cell wall-perturbing agents. The Δpmt mutants also show defects in developmental patterning. Germ tube emergence is early in ΔpmtA and more frequent in ΔpmtC mutants than in the wild type. In ΔpmtB mutants, intrahyphal hyphae develop. All Δpmt mutants show distinct conidiophore defects. The ΔpmtA strain has swollen vesicles and conidiogenous cells, the ΔpmtB strain has swollen conidiophore stalks, and the ΔpmtC strain has dramatically elongated conidiophore stalks. We also show that AN5660, an ortholog of Saccharomyces cerevisiae Wsc1p, is modified by PmtA and PmtC. The Δpmt phenotypes at elevated temperatures, increased sensitivity to cell wall-perturbing agents and restoration to wild-type growth with osmoticum suggest that A. nidulans Pmts modify proteins in the cell wall integrity pathway. The altered developmental patterns in Δpmt mutants suggest that A. nidulans Pmts modify proteins that serve as spatial cues.

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