scholarly journals Characterization of Pneumocystis carinii PHR1, a pH-Regulated Gene Important for Cell Wall Integrity

2001 ◽  
Vol 183 (23) ◽  
pp. 6740-6745 ◽  
Author(s):  
Theodore J. Kottom ◽  
Charles F. Thomas ◽  
Andrew H. Limper
Keyword(s):  
Cell Wall ◽  
Pneumocystis Carinii ◽  
Wall Stress ◽  
Cell Wall Integrity ◽  
Predicted Amino Acid Sequence ◽  
Fungal Cell ◽  
Reading Frame ◽  
Genes Encoding ◽  
Opportunistic Fungal Pathogen ◽  
Fungal Genes

ABSTRACT Pneumocystis carinii remains an important opportunistic fungal pathogen causing life-threatening pneumonia in patients with AIDS and malignancy. Currently, little is known about how the organism adapts to environmental stresses and maintains its cellular integrity. We recently discovered an open reading frame approximately 600 bp downstream of the region codingGSC-1, a gene mediating β-glucan cell wall synthesis in P. carinii. The predicted amino acid sequence of this new gene, termed P. carinii PHR1, exhibited 38% homology to Saccharomyces cerevisiae GAS1, a glycosylphosphatidylinositol-anchored protein essential to maintaining cell wall integrity, and 37% homology to Candida albicans PHR1/PHR2, pH-responsive genes encoding proteins recently implicated in cross-linking β-1,3- and β-1,6-glucans. In view of its homology to these related fungal genes, the pH-dependent expression of P. carinii PHR1 was examined. As in C. albicans, P. carinii PHR1 expression was repressed under acidic conditions but induced at neutral and more alkaline pH. PHR1-related proteins have been implicated in glucan cell wall stability under various environmental conditions. Although difficulties with P. carinii culture and transformation have traditionally limited assessment of gene function in the organism itself, we have successfully used heterologous expression of P. carinii genes in related fungi to address functional correlates of P. carinii-encoded proteins. Therefore, the potential role of P. carinii PHR1 in cell wall integrity was examined by assessing its ability to rescue an S. cerevisiae gas1 mutant with absent endogenous Phr1p-like activity. Interestingly, P. carinii PHR1 DNA successfully restored proliferation of S. cerevisiae gas1 mutants under lethal conditions of cell wall stress. These results indicate that P. carinii PHR1encodes a protein responsive to environmental pH and capable of mediating fungal cell wall integrity.

scholarly journals Deletion of YLR358C Contributes to Reduce Cell Wall Integrity in Saccharomyces Cerevisiae

2022 ◽  
Author(s):  
Yu Zhang ◽  
Mengyan Li ◽  
Hanying Wang ◽  
Juqing Deng ◽  
Jianxing Liu ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Sodium Dodecyl ◽  
Wall Stress ◽  
Pathogenic Fungi ◽  
Cell Wall Integrity ◽  
Calcofluor White ◽  
Fungal Cell ◽  
Reading Frame ◽  
Stress Signals

Abstract The mechanism of fungal cell wall synthesis and assembly is still unclear. Saccharomyces cerevisiae (S. cerevisiae) and pathogenic fungi are conserved in cell wall construction and response to stress signals, and often respond to cell wall stress through activated cell wall integrity (CWI) pathways. Whether the YLR358C open reading frame regulates CWI remains unclear. This study found that the growth of S. cerevisiae with YLR358C knockout was significantly inhibited on the medium containing different concentrations of cell wall interfering agents Calcofluor White (CFW), Congo Red (CR) and sodium dodecyl sulfate (SDS). CFW staining showed that the cell wall chitin was down-regulated, and transmission electron microscopy also observed a decrease in cell wall thickness. Transcriptome sequencing and analysis showed that YLR358C gene may be involved in the regulation of CWI signaling pathway. It was found by qRT-PCR that WSC3, SWI4 and HSP12 were differentially expressed after YLR358C was knocked out. The above results suggest that YLR358C may regulate the integrity of the yeast cell walls and has some potential for application in fermentation.

scholarly journals Balancing of the mitotic exit network and cell wall integrity signaling governs the development and pathogenicity in Magnaporthe oryzae

2021 ◽  
Vol 17 (1) ◽  
pp. e1009080
Author(s):  
Wanzhen Feng ◽  
Ziyi Yin ◽  
Haowen Wu ◽  
Peng Liu ◽  
Xinyu Liu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Magnaporthe Oryzae ◽  
Wall Stress ◽  
Mitotic Exit ◽  
Cellular Growth ◽  
Cell Wall Integrity ◽  
Fungal Cell ◽  
Blast Fungus ◽  
Mitotic Exit Network

The fungal cell wall plays an essential role in maintaining cell morphology, transmitting external signals, controlling cell growth, and even virulence. Relaxation and irreversible stretching of the cell wall are the prerequisites of cell division and development, but they also inevitably cause cell wall stress. Both Mitotic Exit Network (MEN) and Cell Wall Integrity (CWI) are signaling pathways that govern cell division and cell stress response, respectively, how these pathways cross talk to govern and coordinate cellular growth, development, and pathogenicity remains not fully understood. We have identified MoSep1, MoDbf2, and MoMob1 as the conserved components of MEN from the rice blast fungus Magnaporthe oryzae. We have found that blocking cell division results in abnormal CWI signaling. In addition, we discovered that MoSep1 targets MoMkk1, a conserved key MAP kinase of the CWI pathway, through protein phosphorylation that promotes CWI signaling. Moreover, we provided evidence demonstrating that MoSep1-dependent MoMkk1 phosphorylation is essential for balancing cell division with CWI that maintains the dynamic stability required for virulence of the blast fungus.

scholarly journals Our Paths Might Cross: the Role of the Fungal Cell Wall Integrity Pathway in Stress Response and Cross Talk with Other Stress Response Pathways

2009 ◽  
Vol 8 (11) ◽  
pp. 1616-1625 ◽  
Author(s):  
Beth Burgwyn Fuchs ◽  
Eleftherios Mylonakis
Keyword(s):  
Cell Wall ◽  
Stress Response ◽  
Protein Kinase ◽  
Cross Talk ◽  
Wall Stress ◽  
Stress Conditions ◽  
Mapk Cascade ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Fungal Cell

ABSTRACT Fungi occupy diverse environments and are subjected to many extreme conditions. Among the stressful conditions faced by fungi are pH changes, osmotic changes, thermal changes, oxide radicals, nutrient deprivation, and exposure to chemicals. These adversities can be found either in the environment or in animal and human hosts. The cell wall integrity (CWI) pathway provides a means to fortify and repair damages to the cell wall in order to withstand stressful environments. The CWI pathway in comprised of cell wall stress sensors that lead to activation of a mitogen-activated protein kinase (MAPK) cascade. Signaling through the MAPK cascade leads to expression of transcription factors that facilitate biosynthesis of cell wall components and actin organization. Given the relatively limited number of components of the CWI pathway and the very diverse stimuli, there must be a means of expanding the pathway. To manage the diverse stress conditions, the CWI pathway cross talks with other pathways or proteins, and these cross talk events enhance the signaling capabilities of the CWI pathway. Lateral influences that facilitate maintaining the cell wall under stress conditions are TOR signaling, calcineurin signaling, the high-osmolarity glycerol pathway, the cyclic AMP-protein kinase A pathway, and additional proteins. In this article, we highlight several of the cross talk events that have been described for Saccharomyces cerevisiae and several other fungi.

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 A novel connection between the Cell Wall Integrity and the PKA pathways regulates cell wall stress response in yeast

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Raúl García ◽  
Enrique Bravo ◽  
Sonia Diez-Muñiz ◽  
Cesar Nombela ◽  
Jose M. Rodríguez-Peña ◽  
...  
Keyword(s):  
Cell Wall ◽  
Stress Response ◽  
Wall Stress ◽  
Cell Wall Integrity ◽  
Cell Wall Stress

scholarly journals Targeting a critical step in fungal hexosamine biosynthesis

2020 ◽  
Vol 295 (26) ◽  
pp. 8678-8691 ◽  
Author(s):  
Deborah E. A. Lockhart ◽  
Mathew Stanley ◽  
Olawale G. Raimi ◽  
David A. Robinson ◽  
Dominika Boldovjakova ◽  
...  
Keyword(s):  
Cell Wall ◽  
Antifungal Drugs ◽  
Fungal Cell Wall ◽  
Fungal Cell ◽  
Hexosamine Biosynthetic Pathway ◽  
Hexosamine Biosynthesis ◽  
Key Enzyme ◽  
Opportunistic Fungal Pathogen ◽  
Extracellular Environment ◽  
Chemical Evidence

Aspergillus fumigatus is a human opportunistic fungal pathogen whose cell wall protects it from the extracellular environment including host defenses. Chitin, an essential component of the fungal cell wall, is synthesized from UDP-GlcNAc produced in the hexosamine biosynthetic pathway. As this pathway is critical for fungal cell wall integrity, the hexosamine biosynthesis enzymes represent potential targets of antifungal drugs. Here, we provide genetic and chemical evidence that glucosamine 6-phosphate N-acetyltransferase (Gna1), a key enzyme in this pathway, is an exploitable antifungal drug target. GNA1 deletion resulted in loss of fungal viability and disruption of the cell wall, phenotypes that could be rescued by exogenous GlcNAc, the product of the Gna1 enzyme. In a murine model of aspergillosis, the Δgna1 mutant strain exhibited attenuated virulence. Using a fragment-based approach, we discovered a small heterocyclic scaffold that binds proximal to the Gna1 active site and can be optimized to a selective submicromolar binder. Taken together, we have provided genetic, structural, and chemical evidence that Gna1 is an antifungal target in A. fumigatus.

scholarly journals KRE5 Suppression Induces Cell Wall Stress and Alternative ER Stress Response Required for Maintaining Cell Wall Integrity in Candida glabrata

PLoS ONE ◽  
2016 ◽  
Vol 11 (8) ◽  
pp. e0161371 ◽  
Author(s):  
Yutaka Tanaka ◽  
Masato Sasaki ◽  
Fumie Ito ◽  
Toshio Aoyama ◽  
Michiyo Sato-Okamoto ◽  
...  
Keyword(s):  
Cell Wall ◽  
Stress Response ◽  
Er Stress ◽  
Candida Glabrata ◽  
Wall Stress ◽  
Cell Wall Integrity ◽  
Er Stress Response ◽  
Cell Wall Stress

scholarly journals The Transcription Factor SomA Synchronously Regulates Biofilm Formation and Cell Wall Homeostasis in Aspergillus fumigatus

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Yuan Chen ◽  
Francois Le Mauff ◽  
Yan Wang ◽  
Ruiyang Lu ◽  
Donald C. Sheppard ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Biofilm Formation ◽  
Wall Stress ◽  
Fungal Cell ◽  
Glucan Synthase ◽  
Content Type ◽  
Cell Wall Stress ◽  
Chitin Synthases

ABSTRACT Polysaccharides are key components of both the fungal cell wall and biofilm matrix. Despite having distinct assembly and regulation pathways, matrix exopolysaccharide and cell wall polysaccharides share common substrates and intermediates in their biosynthetic pathways. It is not clear, however, if the biosynthetic pathways governing the production of these polysaccharides are cooperatively regulated. Here, we demonstrate that cell wall stress promotes production of the exopolysaccharide galactosaminogalactan (GAG)-depend biofilm formation in the major fungal pathogen of humans Aspergillus fumigatus and that the transcription factor SomA plays a crucial role in mediating this process. A core set of SomA target genes were identified by transcriptome sequencing and chromatin immunoprecipitation coupled to sequencing (ChIP-Seq). We identified a novel SomA-binding site in the promoter regions of GAG biosynthetic genes agd3 and ega3, as well as its regulators medA and stuA. Strikingly, this SomA-binding site was also found in the upstream regions of genes encoding the cell wall stress sensors, chitin synthases, and β-1,3-glucan synthase. Thus, SomA plays a direct regulation of both GAG and cell wall polysaccharide biosynthesis. Consistent with these findings, SomA is required for the maintenance of normal cell wall architecture and compositions in addition to its function in biofilm development. Moreover, SomA was found to globally regulate glucose uptake and utilization, as well as amino sugar and nucleotide sugar metabolism, which provides precursors for polysaccharide synthesis. Collectively, our work provides insight into fungal adaptive mechanisms in response to cell wall stress where biofilm formation and cell wall homeostasis were synchronously regulated. IMPORTANCE The cell wall is essential for fungal viability and is absent from human hosts; thus, drugs disrupting cell wall biosynthesis have gained more attention. Caspofungin is a member of a new class of clinically approved echinocandin drugs to treat invasive aspergillosis by blocking β-1,3-glucan synthase, thus damaging the fungal cell wall. Here, we demonstrate that caspofungin and other cell wall stressors can induce galactosaminogalactan (GAG)-dependent biofilm formation in the human pathogen Aspergillus fumigatus. We further identified SomA as a master transcription factor playing a dual role in both biofilm formation and cell wall homeostasis. SomA plays this dual role by direct binding to a conserved motif upstream of GAG biosynthetic genes and genes involved in cell wall stress sensors, chitin synthases, and β-1,3-glucan synthase. Collectively, these findings reveal a transcriptional control pathway that integrates biofilm formation and cell wall homeostasis and suggest SomA as an attractive target for antifungal drug development.

scholarly journals VelA and LaeA are Key Regulators of Epichloë festucae Transcriptomic Response during Symbiosis with Perennial Ryegrass

2019 ◽  
Vol 8 (1) ◽  
pp. 33 ◽  
Author(s):  
Mostafa Rahnama ◽  
Paul Maclean ◽  
Damien J. Fleetwood ◽  
Richard D. Johnson
Keyword(s):  
Cell Wall ◽  
Secondary Metabolism ◽  
Perennial Ryegrass ◽  
Global Regulator ◽  
Symbiotic Interaction ◽  
Fungal Cell ◽  
Transcriptomic Response ◽  
Epichloë Festucae ◽  
Genes Encoding ◽  
The Impact

VelA (or VeA) is a key global regulator in fungal secondary metabolism and development which we previously showed is required during the symbiotic interaction of Epichloë festucae with perennial ryegrass. In this study, comparative transcriptomic analyses of ∆velA mutant compared to wild-type E. festucae, under three different conditions (in culture, infected seedlings, and infected mature plants), were performed to investigate the impact of VelA on E. festucae transcriptome. These comparative transcriptomic studies showed that VelA regulates the expression of genes encoding proteins involved in membrane transport, fungal cell wall biosynthesis, host cell wall degradation, and secondary metabolism, along with a number of small secreted proteins and a large number of proteins with no predictable functions. In addition, these results were compared with previous transcriptomic experiments that studied the impact of LaeA, another key global regulator of secondary metabolism and development that we have shown is important for E. festucae–perennial ryegrass interaction. The results showed that although VelA and LaeA regulate a subset of E. festucae genes in a similar manner, they also regulated many other genes independently of each other suggesting specialised roles.

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