scholarly journals Global Cell Surface Conformational Shift Mediated by a Candida albicans Adhesin

2004 ◽  
Vol 72 (9) ◽  
pp. 4948-4955 ◽  
Author(s):  
Jason M. Rauceo ◽  
Nand K. Gaur ◽  
Kyeng-Gea Lee ◽  
John E. Edwards ◽  
Stephen A. Klotz ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Cell Surface ◽  
Cell Surface Hydrophobicity ◽  
Cell Aggregation ◽  
Surface Hydrophobicity ◽  
Cellular Adhesion ◽  
Metabolic Inhibitors ◽  
Signal Transduction Inhibitors ◽  
Ordered Aggregation ◽  
Mediate Cell

ABSTRACT Candida albicans maintains both commensal and pathogenic states in humans. Both states are dependent on cell surface-expressed adhesins, including those of the Als family. Heterologous expression of Als5p at the surface of Saccharomyces cerevisiae results in Als5p-mediated adhesion to various ligands, followed by formation of multicellular aggregates. Following adhesion of one region of the cell to fibronectin-coated beads, the entire surface of the cells became competent to mediate cell-cell aggregation. Aggregates formed in the presence of metabolic inhibitors or signal transduction inhibitors but were reduced in the presence of 8-anilino-1-naphthalene-sulfonic acid (ANS) or Congo Red (CR), perturbants that inhibit protein structural transitions. These perturbants also inhibited aggregation of C. albicans. An increase in ANS fluorescence, which accompanied Als-dependent cellular adhesion, indicated an increase in cell surface hydrophobicity. In addition, C. albicans and Als5p-expressing S. cerevisiae showed an aggregation-induced birefringence indicative of order on the cell surface. The increase in birefringence did not occur in the presence of the aggregation disruptants ANS and CR. These results suggest a model for Als5p-mediated aggregation in which an adhesion-triggered change in the conformation of Als5p propagates around the cell surface, forming ordered aggregation-competent regions.

The Candida albicans pH-regulated KER1 gene encodes a lysine/glutamic-acid-rich plasma-membrane protein that is involved in cell aggregation

Microbiology ◽  
2004 ◽  
Vol 150 (8) ◽  
pp. 2641-2651 ◽  
Author(s):  
Amparo Galán ◽  
Manuel Casanova ◽  
Amelia Murgui ◽  
Donna M. MacCallum ◽  
Frank C. Odds ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Plasma Membrane ◽  
Glutamic Acid ◽  
Germ Tube ◽  
Cell Surface Hydrophobicity ◽  
Cell Aggregation ◽  
Surface Hydrophobicity ◽  
Amino Acid Sequences ◽  
Calcofluor White

Immunoscreening of a Candida albicans cDNA library with a polyclonal germ-tube-specific antibody (pAb anti-gt) resulted in the isolation of a gene encoding a lysine/glutamic-acid-rich protein, which was consequently designated KER1. The nucleotide and deduced amino acid sequences of this gene displayed no significant homology with any other known sequence. KER1 encodes a 134 kDa lysine (14·5 %)/glutamic acid (16·7 %) protein (Ker1p) that contains two potential transmembrane segments. KER1 was expressed in a pH-conditional manner, with maximal expression at alkaline pH and lower expression at pH 4·0, and was regulated by RIM101. A Δker1/Δker1 null mutant grew normally but was hyperflocculant under germ-tube-inducing conditions, yet this behaviour was also observed in stationary-phase cells grown under other incubation conditions. Western blotting analysis of different subcellular fractions, using as a probe a monospecific polyclonal antibody raised against a highly antigenic domain of Ker1p (pAb anti-Ker1p), revealed the presence of a 134 kDa band in the purified plasma-membrane fraction from the wild-type strain that was absent in the homologous preparation from Δker1/Δker1 mutant. The pattern of cell-wall protein and mannoprotein species released by digestion with β-glucanases, reactive towards pAbs anti-gt and anti-Ker1p, as well as against concanavalin A, was also different in the Δker1/Δker1 mutant. Mutant strains also displayed an increased cell-surface hydrophobicity and sensitivity to Congo red and Calcofluor white. Overall, these findings indicate that the mutant strain was affected in cell-wall composition and/or structure. The fact that the ker1 mutant had attenuated virulence in systemic mouse infections suggests that this surface protein is also important in host–fungus interactions.

scholarly journals Cloning and Analysis of a Candida albicans Gene That Affects Cell Surface Hydrophobicity

2001 ◽  
Vol 183 (12) ◽  
pp. 3582-3588 ◽  
Author(s):  
David R. Singleton ◽  
James Masuoka ◽  
Kevin C. Hazen
Keyword(s):  
Monoclonal Antibody ◽  
Candida Albicans ◽  
Cell Surface ◽  
Gene Sequence ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Peptide Sequence ◽  
Mass Spectrometry Analysis ◽  
Pathogenic Yeast ◽  
Dna Database

ABSTRACT The opportunistic pathogenic yeast Candida albicansexhibits growth phase-dependent changes in cell surface hydrophobicity, which has been correlated with adhesion to host tissues. Cell wall proteins that might contribute to the cell surface hydrophobicity phenotype were released by limited glucanase digestion. These proteins were initially characterized by their rates of retention during hydrophobic interaction chromatography–high-performance liquid chromatography and used as immunogens for monoclonal antibody production. The present work describes the cloning and functional analysis of a C. albicans gene encoding a 38-kDa protein recognized by the monoclonal antibody 6C5-H4CA. The 6C5-H4CA antigen was resolved by two-dimensional electrophoresis, and a partial protein sequence was determined by mass spectrometry analysis of tryptic fragments. The obtained peptides were used to identify the gene sequence from the unannotated C. albicans DNA database. The antibody epitope was provisionally mapped by peptide display panning, and a peptide sequence matching the epitope was identified in the gene sequence. The gene sequence encodes a novel open reading frame (ORF) of unknown function that is highly similar to several otherC. albicans ORFs and to a single Saccharomyces cerevisiae ORF. Knockout of the gene resulted in a decrease in measurable cell surface hydrophobicity and in adhesion of C. albicans to fibronectin. The results suggest that the 38-kDa protein is a hydrophobic surface protein that meditates binding to host target proteins.

Differential surface localization and temperature-dependent expression of the Candida albicans CSH1 protein

Microbiology ◽  
2004 ◽  
Vol 150 (2) ◽  
pp. 285-292 ◽  
Author(s):  
David R. Singleton ◽  
Kevin C. Hazen
Keyword(s):  
Candida Albicans ◽  
Cell Surface ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Growth Conditions ◽  
Northern Blotting ◽  
Temperature Dependent ◽  
Cell Surface Biotinylation ◽  
Extracellular Compartment ◽  
Primary Amino

Cell-surface hydrophobicity (CSH) in Candida albicans contributes to virulence and can be conveniently regulated in planktonic cultures by altering growth temperature. The CSH1 gene is the first candidate gene that has been demonstrated to play a role in affecting the CSH phenotype. However, the primary amino acid sequence of the CSH1 gene product suggests that the protein should be restricted to the cytoplasm. A majority of the protein appears to demonstrate that localization. Cell-surface biotinylation and limited glucanase digestion were used to determine and estimate the relative amount of Csh1p in the extracellular compartment in comparison to the cytoplasmic pool. Additionally, Western and Northern blotting were used to assess expression of the CSH1 gene under different growth conditions. Compared with cells grown at 23 °C, the total cellular levels of Csh1p are significantly greater at elevated growth temperatures. Detection of Csh1p on the cell surface correlates with the level of overall protein expression. The temperature-dependent regulation and surface presentation of Csh1p suggests a mechanism for regulating the CSH phenotype.

scholarly journals Cell Wall-Anchored CshA Polypeptide (259 Kilodaltons) in Streptococcus gordonii Forms Surface Fibrils That Confer Hydrophobic and Adhesive Properties

1999 ◽  
Vol 181 (10) ◽  
pp. 3087-3095 ◽  
Author(s):  
Roderick McNab ◽  
Helen Forbes ◽  
Pauline S. Handley ◽  
Diane M. Loach ◽  
Gerald W. Tannock ◽  
...  
Keyword(s):  
Cell Surface ◽  
Insertional Mutagenesis ◽  
Cell Surface Hydrophobicity ◽  
Cell Aggregation ◽  
Surface Hydrophobicity ◽  
Streptococcus Gordonii ◽  
Adhesive Properties ◽  
Specific Antibodies ◽  
Structural And Functional Properties ◽  
Human Fibronectin

ABSTRACT It has been shown previously that inactivation of thecshA gene, encoding a major cell surface polypeptide (259 kDa) in the oral bacterium Streptococcus gordonii, generates mutants that are markedly reduced in hydrophobicity, deficient in binding to oral Actinomyces species and to human fibronectin, and unable to colonize the oral cavities of mice. We now show further that surface fibrils 60.7 ± 14.5 nm long, which are present on wild-type S. gordonii DL1 (Challis) cells, bind CshA-specific antibodies and are absent from the cell surfaces ofcshA mutants. To more precisely determine the structural and functional properties of CshA, already inferred from insertional-mutagenesis experiments, we have cloned the entirecshA gene into the replicative plasmid pAM401 and expressed full-length CshA polypeptide on the cell surface of heterologousEnterococcus faecalis JH2-2. Enterococci expressing CshA exhibited a 30-fold increase in cell surface hydrophobicity overE. faecalis JH2-2 carrying the pAM401 vector alone and 2.4-fold-increased adhesion to human fibronectin. CshA expression inE. faecalis also promoted cell-cell aggregation and increased the ability of enterococci to bind Actinomyces naeslundii cells. Electron micrographs of negatively stainedE. faecalis cells expressing CshA showed peritrichous surface fibrils 70.3 ± 9.1 nm long that were absent from controlE. faecalis JH2-2(pAM401) cells. The fibrils bound CshA-specific antibodies, as detected by immunoelectron microscopy, and the antibodies inhibited the adhesion of E. faecalis cells to fibronectin. The results demonstrate that the CshA polypeptide is the structural and functional component of S. gordoniiadhesive fibrils, and they provide a molecular basis for past correlations of surface fibril production, cell surface hydrophobicity, and adhesion in species of oral “sanguis-like” streptococci.

scholarly journals cDNA Microarray Analysis of Differential Gene Expression in Candida albicans Biofilm Exposed to Farnesol

2005 ◽  
Vol 49 (2) ◽  
pp. 584-589 ◽  
Author(s):  
Ying-Ying Cao ◽  
Yong-Bing Cao ◽  
Zheng Xu ◽  
Kang Ying ◽  
Yao Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Drug Resistance ◽  
Candida Albicans ◽  
Cell Surface ◽  
Microarray Analysis ◽  
Biofilm Formation ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Cdna Microarray Analysis ◽  
Hyphal Formation

ABSTRACT Candida albicans biofilms are structured microbial communities with high levels of drug resistance. Farnesol, a quorum-sensing molecule that inhibits hyphal formation in C. albicans, has been found to prevent biofilm formation by C. albicans. There is limited information, however, about the molecular mechanism of farnesol against biofilm formation. We used cDNA microarray analysis to identify the changes in the gene expression profile of a C. albicans biofilm inhibited by farnesol. Confocal scanning laser microscopy was used to visualize and confirm normal and farnesol-inhibited biofilms. A total of 274 genes were identified as responsive, with 104 genes up-regulated and 170 genes down-regulated. Independent reverse transcription-PCR analysis was used to confirm the important changes detected by microarray analysis. In addition to hyphal formation-associated genes (e.g., TUP1, CRK1, and PDE2), a number of other genes with roles related to drug resistance (e.g., FCR1 and PDR16), cell wall maintenance (e.g., CHT2 and CHT3), and iron transport (e.g., FTR2) were responsive, as were several genes encoding heat shock proteins (e.g., HSP70, HSP90, HSP104, CaMSI3, and SSA2). Further study of these differentially regulated genes is warranted to evaluate how they may be involved in C. albicans biofilm formation. Consistent with the down-regulation of the cell surface hydrophobicity-associated gene (CSH1), the water-hydrocarbon two-phase assay showed a decrease in cell surface hydrophobicity in the farnesol-treated group compared to that in the control group. Our data provide new insight into the molecular mechanism of farnesol against C. albicans biofilm formation.

Hydrophobic cell wall protein glycosylation by the pathogenic fungus Candida albicans

1994 ◽  
Vol 40 (4) ◽  
pp. 266-272 ◽  
Author(s):  
Kevin C. Hazen ◽  
Pati M. Glee
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Cell Surface ◽  
Molecular Mass ◽  
Pathogenic Fungus ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Protein Glycosylation ◽  
Yeast Cells ◽  
Cell Wall Proteins

Cell surface hydrophobicity influences adhesion and virulence of the opportunistic fungal pathogen Candida albicans. Previous studies have shown that cell surface hydrophobicity is due to specific proteins that are exposed on hydrophobic cells but are masked by long fibrils on hydrophilic cells. This observation suggests that hydrophobic cell wall proteins may contain little or no mannosylation. In the present study, the glycosylation levels of three hydrophobic cell wall proteins (molecular mass range between 36 and 40 kDa) derived from yeast cells were examined. One hydrophilic protein (90 kDa) was also tested. Various endoglycosidases (endoglycosidase F – N-glycosidase F, O-glycosidase, β-mannosidase, N-glycosidase F), an exoglycosidase (α-mannosidase), and trifluoromethane sulfonic acid were used to deglycosylate the proteins. All four proteins were reactive to the lectin concanavalin A, demonstrating that they were mannoproteins. However, gel electrophoresis of the control and treated proteins revealed that mannosyl groups of hydrophobic proteins were less than 2 kDa in size, while the mannosyl group of the hydrophilic protein had a molecular mass of approximately 20 kDa. These results suggest that unlike many hydrophilic proteins, hydrophobic proteins may have low levels of glycosylation. Changes in glycosylation may determine exposure of hydrophobic protein regions at the cell surface.Key words: Candida albicans, cell wall, mannoproteins, hydrophobicity, fibrils.

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