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Fibronectin-, vitronectin- and laminin-binding proteins at the cell walls of Candida parapsilosis and Candida tropicalis pathogenic yeasts.

Kozik A, Karkowska-Kuleta J, Zajac D, Bochenska O, Kedracka-Krok S, Jankowska U, Rapala-Kozik M - BMC Microbiol. (2015)

Bottom Line: The major individual compounds of the fungal cell wall that bound fibronectin, vitronectin and laminin were found to comprise two groups: (1) true cell wall components similar to C. albicans adhesins from the Als, Hwp and Iff/Hyr families; and (2) atypical (cytoplasm-derived) surface-exposed proteins, including malate synthase, glucose-6-phosphate isomerase, 6-phosphogluconate dehydrogenase, enolase, fructose-1,6-bisphosphatase, transketolase, transaldolase and elongation factor 2.The adhesive abilities of two investigated non-albicans Candida species toward extracellular matrix proteins were comparable to those of C. albicans suggesting an important role of this particular virulence attribute in the pathogenesis of infections caused by C. tropicalis and C. parapsilosis.Our results reveal new insight into host-pathogen interactions during infections by two important, recently emerging, fungal pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30-387, Krakow, Poland. andrzej.kozik@uj.edu.pl.

ABSTRACT

Background: Candida parapsilosis and C. tropicalis increasingly compete with C. albicans-the most common fungal pathogen in humans-as causative agents of severe candidiasis in immunocompromised patients. In contrast to C. albicans, the pathogenic mechanisms of these two non-albicans Candida species are poorly understood. Adhesion of Candida yeast to host cells and the extracellular matrix is critical for fungal invasion of hosts.

Methods: The fungal proteins involved in interactions with extracellular matrix proteins were isolated from mixtures of β-1,3-glucanase- or β-1,6-glucanase-extractable cell wall-associated proteins by use of affinity chromatography and chemical cross-linking methods, and were further identified by liquid chromatography-coupled tandem mass spectrometry.

Results: In the present study, we characterized the binding of three major extracellular matrix proteins-fibronectin, vitronectin and laminin-to C. parapsilosis and C. tropicalis pseudohyphae. The major individual compounds of the fungal cell wall that bound fibronectin, vitronectin and laminin were found to comprise two groups: (1) true cell wall components similar to C. albicans adhesins from the Als, Hwp and Iff/Hyr families; and (2) atypical (cytoplasm-derived) surface-exposed proteins, including malate synthase, glucose-6-phosphate isomerase, 6-phosphogluconate dehydrogenase, enolase, fructose-1,6-bisphosphatase, transketolase, transaldolase and elongation factor 2.

Discussion: The adhesive abilities of two investigated non-albicans Candida species toward extracellular matrix proteins were comparable to those of C. albicans suggesting an important role of this particular virulence attribute in the pathogenesis of infections caused by C. tropicalis and C. parapsilosis.

Conclusions: Our results reveal new insight into host-pathogen interactions during infections by two important, recently emerging, fungal pathogens.

No MeSH data available.


Related in: MedlinePlus

Involvement of the major C. parapsilosis and C. tropicalis cell wall components in the binding of ECMPs. Binding of biotinylated fibronectin (FN) (a), vitronectin (VTN) (b) and laminin (LAM) (c) was determined for C. parapsilosis and C. tropicalis pseudohyphae (obtained from 5 × 108 yeast cells) that were pretreated with enzymes that digest the major constituents of the fungal cell wall, namely: (1) a mixture of α1-2,3 mannosidase and α1-6 mannosidase; (2) proteinase K; and (3) β-1,3-glucanase. The cell suspensions were then incubated with 100 nM of each labeled ECMP for 1.5 h at 37 °C. The amount of bound protein was determined using the SA-HRP/TMB detection system. The binding level of the control (untreated) cells was considered 100 %. Bars represent the mean values of three determinations (three independent yeast cultures) ± standard deviation. Statistical significance levels against the control are indicated with *p < 0.05, ***p < 0.001 or ns “not significant”, whereas statistically significant comparisons between two tested species are marked with # (p < 0.05)
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Fig2: Involvement of the major C. parapsilosis and C. tropicalis cell wall components in the binding of ECMPs. Binding of biotinylated fibronectin (FN) (a), vitronectin (VTN) (b) and laminin (LAM) (c) was determined for C. parapsilosis and C. tropicalis pseudohyphae (obtained from 5 × 108 yeast cells) that were pretreated with enzymes that digest the major constituents of the fungal cell wall, namely: (1) a mixture of α1-2,3 mannosidase and α1-6 mannosidase; (2) proteinase K; and (3) β-1,3-glucanase. The cell suspensions were then incubated with 100 nM of each labeled ECMP for 1.5 h at 37 °C. The amount of bound protein was determined using the SA-HRP/TMB detection system. The binding level of the control (untreated) cells was considered 100 %. Bars represent the mean values of three determinations (three independent yeast cultures) ± standard deviation. Statistical significance levels against the control are indicated with *p < 0.05, ***p < 0.001 or ns “not significant”, whereas statistically significant comparisons between two tested species are marked with # (p < 0.05)

Mentions: Involvement of major classes of fungal cell wall components, namely, cell wall-associated proteins, glucans and mannans, was tested by determination of the binding of each ECMP to pseudohyphae that were pretreated with: (1) proteinase K, which digests proteins exposed on the surface of fungal cells; (2) β-1,3-glucanase, which hydrolyzes the β-1,3-glucan network and also releases a set of β-1,3-glucan–associated proteins; and (3) a mixture of mannosidases, which degrade the mannan layer of the cell wall. As shown in Fig. 2, the cell wall-associated proteins play a predominant role in ECMP binding in both Candida species investigated. Of other cell wall components, apart from proteins, mannans were additionally found to be important for the binding of fibronectin, as judged from a decrease of the binding level by about 40 % and 20 % for C. parapsilosis and C. tropicalis, respectively, after mannosidase treatment. A statistically significant difference between the effect of β-1,3-glucanase treatment on fibronectin binding in C. parapsilosis and C. tropicalis suggests a lower contribution of β-1,3-glucan to the interactions of C. tropicalis cell wall with this ECMP, relatively to the other species.Fig. 2


Fibronectin-, vitronectin- and laminin-binding proteins at the cell walls of Candida parapsilosis and Candida tropicalis pathogenic yeasts.

Kozik A, Karkowska-Kuleta J, Zajac D, Bochenska O, Kedracka-Krok S, Jankowska U, Rapala-Kozik M - BMC Microbiol. (2015)

Involvement of the major C. parapsilosis and C. tropicalis cell wall components in the binding of ECMPs. Binding of biotinylated fibronectin (FN) (a), vitronectin (VTN) (b) and laminin (LAM) (c) was determined for C. parapsilosis and C. tropicalis pseudohyphae (obtained from 5 × 108 yeast cells) that were pretreated with enzymes that digest the major constituents of the fungal cell wall, namely: (1) a mixture of α1-2,3 mannosidase and α1-6 mannosidase; (2) proteinase K; and (3) β-1,3-glucanase. The cell suspensions were then incubated with 100 nM of each labeled ECMP for 1.5 h at 37 °C. The amount of bound protein was determined using the SA-HRP/TMB detection system. The binding level of the control (untreated) cells was considered 100 %. Bars represent the mean values of three determinations (three independent yeast cultures) ± standard deviation. Statistical significance levels against the control are indicated with *p < 0.05, ***p < 0.001 or ns “not significant”, whereas statistically significant comparisons between two tested species are marked with # (p < 0.05)
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Related In: Results  -  Collection

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Fig2: Involvement of the major C. parapsilosis and C. tropicalis cell wall components in the binding of ECMPs. Binding of biotinylated fibronectin (FN) (a), vitronectin (VTN) (b) and laminin (LAM) (c) was determined for C. parapsilosis and C. tropicalis pseudohyphae (obtained from 5 × 108 yeast cells) that were pretreated with enzymes that digest the major constituents of the fungal cell wall, namely: (1) a mixture of α1-2,3 mannosidase and α1-6 mannosidase; (2) proteinase K; and (3) β-1,3-glucanase. The cell suspensions were then incubated with 100 nM of each labeled ECMP for 1.5 h at 37 °C. The amount of bound protein was determined using the SA-HRP/TMB detection system. The binding level of the control (untreated) cells was considered 100 %. Bars represent the mean values of three determinations (three independent yeast cultures) ± standard deviation. Statistical significance levels against the control are indicated with *p < 0.05, ***p < 0.001 or ns “not significant”, whereas statistically significant comparisons between two tested species are marked with # (p < 0.05)
Mentions: Involvement of major classes of fungal cell wall components, namely, cell wall-associated proteins, glucans and mannans, was tested by determination of the binding of each ECMP to pseudohyphae that were pretreated with: (1) proteinase K, which digests proteins exposed on the surface of fungal cells; (2) β-1,3-glucanase, which hydrolyzes the β-1,3-glucan network and also releases a set of β-1,3-glucan–associated proteins; and (3) a mixture of mannosidases, which degrade the mannan layer of the cell wall. As shown in Fig. 2, the cell wall-associated proteins play a predominant role in ECMP binding in both Candida species investigated. Of other cell wall components, apart from proteins, mannans were additionally found to be important for the binding of fibronectin, as judged from a decrease of the binding level by about 40 % and 20 % for C. parapsilosis and C. tropicalis, respectively, after mannosidase treatment. A statistically significant difference between the effect of β-1,3-glucanase treatment on fibronectin binding in C. parapsilosis and C. tropicalis suggests a lower contribution of β-1,3-glucan to the interactions of C. tropicalis cell wall with this ECMP, relatively to the other species.Fig. 2

Bottom Line: The major individual compounds of the fungal cell wall that bound fibronectin, vitronectin and laminin were found to comprise two groups: (1) true cell wall components similar to C. albicans adhesins from the Als, Hwp and Iff/Hyr families; and (2) atypical (cytoplasm-derived) surface-exposed proteins, including malate synthase, glucose-6-phosphate isomerase, 6-phosphogluconate dehydrogenase, enolase, fructose-1,6-bisphosphatase, transketolase, transaldolase and elongation factor 2.The adhesive abilities of two investigated non-albicans Candida species toward extracellular matrix proteins were comparable to those of C. albicans suggesting an important role of this particular virulence attribute in the pathogenesis of infections caused by C. tropicalis and C. parapsilosis.Our results reveal new insight into host-pathogen interactions during infections by two important, recently emerging, fungal pathogens.

View Article: PubMed Central - PubMed

Affiliation: Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30-387, Krakow, Poland. andrzej.kozik@uj.edu.pl.

ABSTRACT

Background: Candida parapsilosis and C. tropicalis increasingly compete with C. albicans-the most common fungal pathogen in humans-as causative agents of severe candidiasis in immunocompromised patients. In contrast to C. albicans, the pathogenic mechanisms of these two non-albicans Candida species are poorly understood. Adhesion of Candida yeast to host cells and the extracellular matrix is critical for fungal invasion of hosts.

Methods: The fungal proteins involved in interactions with extracellular matrix proteins were isolated from mixtures of β-1,3-glucanase- or β-1,6-glucanase-extractable cell wall-associated proteins by use of affinity chromatography and chemical cross-linking methods, and were further identified by liquid chromatography-coupled tandem mass spectrometry.

Results: In the present study, we characterized the binding of three major extracellular matrix proteins-fibronectin, vitronectin and laminin-to C. parapsilosis and C. tropicalis pseudohyphae. The major individual compounds of the fungal cell wall that bound fibronectin, vitronectin and laminin were found to comprise two groups: (1) true cell wall components similar to C. albicans adhesins from the Als, Hwp and Iff/Hyr families; and (2) atypical (cytoplasm-derived) surface-exposed proteins, including malate synthase, glucose-6-phosphate isomerase, 6-phosphogluconate dehydrogenase, enolase, fructose-1,6-bisphosphatase, transketolase, transaldolase and elongation factor 2.

Discussion: The adhesive abilities of two investigated non-albicans Candida species toward extracellular matrix proteins were comparable to those of C. albicans suggesting an important role of this particular virulence attribute in the pathogenesis of infections caused by C. tropicalis and C. parapsilosis.

Conclusions: Our results reveal new insight into host-pathogen interactions during infections by two important, recently emerging, fungal pathogens.

No MeSH data available.


Related in: MedlinePlus