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The MP65 gene is required for cell wall integrity, adherence to epithelial cells and biofilm formation in Candida albicans.

Sandini S, Stringaro A, Arancia S, Colone M, Mondello F, Murtas S, Girolamo A, Mastrangelo N, De Bernardis F - BMC Microbiol. (2011)

Bottom Line: Interestingly, the mp65Δ mutant displayed a marked reduction in adhesion to BEC and Caco-2 cells and severe defects in biofilm formation when compared to the wild type.All of the mentioned properties were totally or partially recovered in a revertant strain, demonstrating the specificity of gene deletion.We demonstrate that the MP65 gene of Candida albicans plays a significant role in maintaining cell wall integrity, as well as in adherence to epithelia and biofilm formation, which are major virulence attributes of this fungus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Infectious, Parasitic and Immuno-mediated Diseases, Istituto Superiore di Sanità, Rome, 00161, Italy. silvia.sandini@iss.it

ABSTRACT

Background: The MP65 gene of Candida albicans (orf19.1779) encodes a putative β-glucanase mannoprotein of 65 kDa, which plays a main role in a host-fungus relationship, morphogenesis and pathogenicity. In this study, we performed an extensive analysis of a mp65Δ mutant to assess the role of this protein in cell wall integrity, adherence to epithelial cells and biofilm formation.

Results: The mp65Δ mutant showed a high sensitivity to a range of cell wall-perturbing and degrading agents, especially Congo red, which induced morphological changes such as swelling, clumping and formation of hyphae. The mp65Δ mutant showed an activation of two MAPKs (Mkc1p and Cek1p), a high level of expression of two stress-related genes (DDR48 and SOD5), and a modulated expression of β-glucan epitopes, but no gross changes in cell wall polysaccharide composition. Interestingly, the mp65Δ mutant displayed a marked reduction in adhesion to BEC and Caco-2 cells and severe defects in biofilm formation when compared to the wild type. All of the mentioned properties were totally or partially recovered in a revertant strain, demonstrating the specificity of gene deletion.

Conclusions: We demonstrate that the MP65 gene of Candida albicans plays a significant role in maintaining cell wall integrity, as well as in adherence to epithelia and biofilm formation, which are major virulence attributes of this fungus.

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Morphological analysis of the mp65Δ mutant. (A) The wild type (wt), mp65Δ mutant (hom) and revertant (rev) strains were grown in YEPD for 24 h at 28°C with or without Congo red (50 μg/ml) and then observed under a light microscope and SEM, as described in the Methods section. The magnification bar corresponds to 15 μm (Panels 1, 2, 4, 6, 7 and 9), 5 μm (Panel 3), and 60 μm (Panels 5 and 8). (B) Pictures show swelling and clumping of the mp65Δ mutant cells after treatment with Congo red. (C) Flocculation analysis. Following o.n. growth, the cultures were transferred to test tubes and left to stand for 10 min. As shown, the filamentous cells (h) of the mp65Δ mutant precipitated to the bottom of the tube (hom: Tube 2). The yeast cells (y) of the wild type (wt: Tube 1) and revertant strains (rev: Tube 3) remained in suspension.
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Figure 3: Morphological analysis of the mp65Δ mutant. (A) The wild type (wt), mp65Δ mutant (hom) and revertant (rev) strains were grown in YEPD for 24 h at 28°C with or without Congo red (50 μg/ml) and then observed under a light microscope and SEM, as described in the Methods section. The magnification bar corresponds to 15 μm (Panels 1, 2, 4, 6, 7 and 9), 5 μm (Panel 3), and 60 μm (Panels 5 and 8). (B) Pictures show swelling and clumping of the mp65Δ mutant cells after treatment with Congo red. (C) Flocculation analysis. Following o.n. growth, the cultures were transferred to test tubes and left to stand for 10 min. As shown, the filamentous cells (h) of the mp65Δ mutant precipitated to the bottom of the tube (hom: Tube 2). The yeast cells (y) of the wild type (wt: Tube 1) and revertant strains (rev: Tube 3) remained in suspension.

Mentions: To study the cell-wall defects in more detail, we performed morphological, chemical, cytochemical and cytofluorimetric studies, mostly in cells responding to Congo red, which was the most intense perturbing agent. As shown in Figures 3A and 3B, Congo red-stressed mp65Δ mutant cells showed severe changes, such as swelling, clumping and formation of pseudohyphae and hyphae, compared with the wild type cells, which showed a normal yeast-shape appearance. The revertant strain showed an intermediate phenotype consisting predominantly of yeasts and some hyphae. Furthermore, the deletion of the MP65 gene affected flocculation: the mp65Δ mutant grown with Congo red showed marked flocs (Figure 3C).


The MP65 gene is required for cell wall integrity, adherence to epithelial cells and biofilm formation in Candida albicans.

Sandini S, Stringaro A, Arancia S, Colone M, Mondello F, Murtas S, Girolamo A, Mastrangelo N, De Bernardis F - BMC Microbiol. (2011)

Morphological analysis of the mp65Δ mutant. (A) The wild type (wt), mp65Δ mutant (hom) and revertant (rev) strains were grown in YEPD for 24 h at 28°C with or without Congo red (50 μg/ml) and then observed under a light microscope and SEM, as described in the Methods section. The magnification bar corresponds to 15 μm (Panels 1, 2, 4, 6, 7 and 9), 5 μm (Panel 3), and 60 μm (Panels 5 and 8). (B) Pictures show swelling and clumping of the mp65Δ mutant cells after treatment with Congo red. (C) Flocculation analysis. Following o.n. growth, the cultures were transferred to test tubes and left to stand for 10 min. As shown, the filamentous cells (h) of the mp65Δ mutant precipitated to the bottom of the tube (hom: Tube 2). The yeast cells (y) of the wild type (wt: Tube 1) and revertant strains (rev: Tube 3) remained in suspension.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 3: Morphological analysis of the mp65Δ mutant. (A) The wild type (wt), mp65Δ mutant (hom) and revertant (rev) strains were grown in YEPD for 24 h at 28°C with or without Congo red (50 μg/ml) and then observed under a light microscope and SEM, as described in the Methods section. The magnification bar corresponds to 15 μm (Panels 1, 2, 4, 6, 7 and 9), 5 μm (Panel 3), and 60 μm (Panels 5 and 8). (B) Pictures show swelling and clumping of the mp65Δ mutant cells after treatment with Congo red. (C) Flocculation analysis. Following o.n. growth, the cultures were transferred to test tubes and left to stand for 10 min. As shown, the filamentous cells (h) of the mp65Δ mutant precipitated to the bottom of the tube (hom: Tube 2). The yeast cells (y) of the wild type (wt: Tube 1) and revertant strains (rev: Tube 3) remained in suspension.
Mentions: To study the cell-wall defects in more detail, we performed morphological, chemical, cytochemical and cytofluorimetric studies, mostly in cells responding to Congo red, which was the most intense perturbing agent. As shown in Figures 3A and 3B, Congo red-stressed mp65Δ mutant cells showed severe changes, such as swelling, clumping and formation of pseudohyphae and hyphae, compared with the wild type cells, which showed a normal yeast-shape appearance. The revertant strain showed an intermediate phenotype consisting predominantly of yeasts and some hyphae. Furthermore, the deletion of the MP65 gene affected flocculation: the mp65Δ mutant grown with Congo red showed marked flocs (Figure 3C).

Bottom Line: Interestingly, the mp65Δ mutant displayed a marked reduction in adhesion to BEC and Caco-2 cells and severe defects in biofilm formation when compared to the wild type.All of the mentioned properties were totally or partially recovered in a revertant strain, demonstrating the specificity of gene deletion.We demonstrate that the MP65 gene of Candida albicans plays a significant role in maintaining cell wall integrity, as well as in adherence to epithelia and biofilm formation, which are major virulence attributes of this fungus.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Infectious, Parasitic and Immuno-mediated Diseases, Istituto Superiore di Sanità, Rome, 00161, Italy. silvia.sandini@iss.it

ABSTRACT

Background: The MP65 gene of Candida albicans (orf19.1779) encodes a putative β-glucanase mannoprotein of 65 kDa, which plays a main role in a host-fungus relationship, morphogenesis and pathogenicity. In this study, we performed an extensive analysis of a mp65Δ mutant to assess the role of this protein in cell wall integrity, adherence to epithelial cells and biofilm formation.

Results: The mp65Δ mutant showed a high sensitivity to a range of cell wall-perturbing and degrading agents, especially Congo red, which induced morphological changes such as swelling, clumping and formation of hyphae. The mp65Δ mutant showed an activation of two MAPKs (Mkc1p and Cek1p), a high level of expression of two stress-related genes (DDR48 and SOD5), and a modulated expression of β-glucan epitopes, but no gross changes in cell wall polysaccharide composition. Interestingly, the mp65Δ mutant displayed a marked reduction in adhesion to BEC and Caco-2 cells and severe defects in biofilm formation when compared to the wild type. All of the mentioned properties were totally or partially recovered in a revertant strain, demonstrating the specificity of gene deletion.

Conclusions: We demonstrate that the MP65 gene of Candida albicans plays a significant role in maintaining cell wall integrity, as well as in adherence to epithelia and biofilm formation, which are major virulence attributes of this fungus.

Show MeSH
Related in: MedlinePlus