Dataset Information

Host carbon sources modulate cell wall architecture, drug resistance and virulence in a fungal pathogen.

ABSTRACT: The survival of all microbes depends upon their ability to respond to environmental challenges. To establish infection, pathogens such as Candida albicans must mount effective stress responses to counter host defences while adapting to dynamic changes in nutrient status within host niches. Studies of C. albicans stress adaptation have generally been performed on glucose-grown cells, leaving the effects of alternative carbon sources upon stress resistance largely unexplored. We have shown that growth on alternative carbon sources, such as lactate, strongly influence the resistance of C. albicans to antifungal drugs, osmotic and cell wall stresses. Similar trends were observed in clinical isolates and other pathogenic Candida species. The increased stress resistance of C. albicans was not dependent on key stress (Hog1) and cell integrity (Mkc1) signalling pathways. Instead, increased stress resistance was promoted by major changes in the architecture and biophysical properties of the cell wall. Glucose- and lactate-grown cells displayed significant differences in cell wall mass, ultrastructure, elasticity and adhesion. Changes in carbon source also altered the virulence of C. albicans in models of systemic candidiasis and vaginitis, confirming the importance of alternative carbon sources within host niches during C. albicans infections.

SUBMITTER: Ene IV

PROVIDER: S-EPMC3465787 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Host carbon sources modulate cell wall architecture, drug resistance and virulence in a fungal pathogen.

Ene Iuliana V IV Adya Ashok K AK Wehmeier Silvia S Brand Alexandra C AC MacCallum Donna M DM Gow Neil A R NA Brown Alistair J P AJ

Cellular microbiology 20120605 9

The survival of all microbes depends upon their ability to respond to environmental challenges. To establish infection, pathogens such as Candida albicans must mount effective stress responses to counter host defences while adapting to dynamic changes in nutrient status within host niches. Studies of C. albicans stress adaptation have generally been performed on glucose-grown cells, leaving the effects of alternative carbon sources upon stress resistance largely unexplored. We have shown that gr ...[more]

PMID: 22587014

Similar Datasets

Project description:UnlabelledThe fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock.ImportanceThe C. albicans cell wall is the first line of defense against external insults, the site of immune recognition by the host, and an attractive target for antifungal therapy. Its tensile strength is conferred by a network of cell wall polysaccharides, which are remodeled in response to growth conditions and environmental stress. However, little is known about how cell wall elasticity is regulated and how it affects adaptation to stresses such as sudden changes in osmolarity. We show that elasticity is critical for survival under conditions of osmotic shock, before stress signaling pathways have time to induce gene expression and drive glycerol accumulation. Critical cell wall remodeling enzymes control cell wall flexibility, and its regulation is strongly dependent on host nutritional inputs. We also demonstrate an entirely new level of cell wall dynamism, where significant architectural changes and structural realignment occur within seconds of an osmotic shock.

Project description:2.3 Cell wall and secretome preparation. C. albicans RM1000 cells grown to mid-exponential phase were harvested by centrifugation. The resulting supernatant was sterile-filtered and then concentrated on 10-kDcut-off filters (Amicon Ultra-15 Centrifugal filter units, Millipore) as described previously [31]. To analyse the wall proteome, cell walls were isolated by hot SDS-extraction. The cell pellet obtained was used to prepare cell walls as described previously [36]. Briefly, the finely ground cell pellet was washed several times with PBS, and then subjected to breakage in a FastPrep bead beater (Savant Instruments Inc., Farmingdale, NY, USA) with glass beads (0.25-0.50 mm, 12-16 runs for 45 sec at speed 6) in the presence of a protease inhibitor cocktail. Full breakage was controlled by light-microscopic inspection. The pellet was washed several times with 1 M NaCl and stored overnight at 4°C. The following day, the pellet was washed several times with MilliQ-water and then boiled four times for 10 min in SDS extraction buffer (150 mM NaCl, 2% (w/v) SDS, 100 mM Na-EDTA, 100 mM β-mercaptoethanol, 50 mM Tris-HCl, pH 7.8), washed with MilliQ-water and lyophilized overnight. The resulting purified wall pellets were either stored at -80°C or directly reduced and S-alkylated [37]. 2.4 Mass spectrometric analyses of cell wall proteomes and secretomes. Lyophilized cell walls were reduced with 10 mM dithiothreitol in 100 mM NH4HCO3 (1 h at 55C). After cooling to room temperature and centrifugation, the supernatant was discarded. The reduced proteins were alkylated with 65 mM iodoacetamide in 100 mM NH4HCO3 for 45 min at room temperature in the dark. The samples were quenched with 55 mM dithiothreitol in 100 mM NH4HCO3 for 5 min. Subsequently, the samples were washed six times with 50 mM NH4HCO3 and either frozen in liquid nitrogen and stored at -80C or digested using 2 µg Trypsin Gold (Promega, Madison,WI) from a 1 µg/µl stock solution for 18 h at 37°C. The concentrated secretome samples were treated similarly, with reduction and alkylation on 10-kD cut-off spin filters (Amicon, Billerica, MA) [32]. The resulting tryptic digests were desalted using a C18 tip column (Varian, Palo Alto, CA) according to the manufacturer’s instructions. After evaporation of acetonitrile with a Speedvac (Genevac, Ipswich, England) the peptide concentration was determined at 205 nm using a NanoDrop ND-1000 (Isogen Life science, IJsselstein, The Netherlands) [38]. Each sample was diluted with 0.1% trifluoroacetic acid to a final concentration of 25 ng/µl, and 10 µl per run were injected onto an Ultimate 2000 nano-HPLC system (LC Packings, Amsterdam, The Netherlands) equipped with a PepMap100 C18 reversed phase column (75 µm inner diameter, 25 cm length; Dionex, Sunnyvale, CA). An elution flow rate of 0.3 µl/min was used along a linear gradient with increasing acetonitrile concentration over 45 min. The eluting peptides were directly ionized by electrospray in a Q-TOF (Micromass, Whyttenshawe, UK). Survey scans were acquired from m/z 350-1200. For low energy collision-induced dissociation (MS/MS), the most intense ions were selected in a data-dependent mode. 2.5 Data processing and analysis. After processing with the MaxEnt3 algorithm (MasslynxProteinlynx), the spectra were converted into pkl (peak list) files (available on PRIDE: www.ebi.ac.uk/pride: accession numbers 22716-22721) . Proteins were identified using MASCOT server 2.3.02 (Matrix Science, UK) and a database (6210 entries) consisting of a complete ORF translation of C. albicans and a list of regularly encountered contaminants. Enzyme was set to trypsin and allowing two miscleavages were allowed. Carbamidomethyl (C) was used as a fixed modification and Oxidation (M) as a variable modification. Mass tolerance and MS/MS tolerance were set to and a tolerance of 0.3 Da0.5 Da. Detected masses were charge deconvoluted to +1. Based on probabilistic MASCOT scoring a P value of < 0.05 was considered significant for peptide identification. At least three independently obtained biological samples were analysed for each condition and each was subjected to two MS/MS runs.

Dataset Information

Host carbon sources modulate cell wall architecture, drug resistance and virulence in a fungal pathogen.

Publications

Host carbon sources modulate cell wall architecture, drug resistance and virulence in a fungal pathogen.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets