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Differential profiles of soluble proteins during the initiation of morphogenesis in Candida albicans
M Niimi1, M G Shepherd, B C Monk
1Experimental Oral Biology Laboratory, Department of Oral Biology and Oral Pathology, School of Dentistry, University of Otago, P.O. Box 647, Dunedin, New Zealand. masa.niimi@stonebow.otago.ac.nz
Abstract:
Candida albicans is a dimorphic fungus that can grow either as yeast or as mycelia. The mycelial form may be required for tissue penetration and therefore may have a role in pathogenesis. The protein profiles of the cell-free S100 fraction from budding yeast cells and germ tube-forming cells (an early stage of the transition between yeast and mycelia) were evaluated using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Yeast growth or germ tube formation was induced in carbon-starved cells at 37 degrees C by either glucose, galactose or N-acetylglucosamine at pH 4.5 or pH 6.7. More than 400 constitutively synthesised polypeptides were identified on 2-D PAGE by silver staining. A few polypeptides which seem to reflect the release from carbon starvation were detected, but no polypeptides unique to either morphology were observed. Fractionation of S100 preparations by polyethylenimine or heparin-agarose affinity chromatography, which have been used to detect DNA-binding proteins, revealed several proteins that were synthesised on the resumption of cell growth or in response to pH difference. Heparin-agarose also bound novel polypeptides in the size range 130-200 kDa that were preferentially synthesised in germ tube-forming cells. These results suggest that any protein factors that might exert a regulatory role early in germ tube formation are of low abundance, and that a minor group of soluble proteins involved in C. albicans morphogenesis may be differentially synthesised.
Insights
Investigating Candida albicans morphogenesis, this study analyzed protein profiles during yeast and germ tube formation. Researchers found no unique proteins for either form but identified novel, low-abundance proteins in germ tube cells, suggesting a role in fungal development.
Area of Science:
- Mycology
- Molecular Biology
- Biochemistry
Background:
- Candida albicans is a dimorphic fungus capable of switching between yeast and mycelial forms.
- The mycelial form is implicated in tissue penetration and pathogenesis.
- Understanding the molecular mechanisms of this morphological transition is crucial for controlling C. albicans infections.
Purpose of the Study:
- To compare the protein profiles of Candida albicans during yeast growth and early germ tube formation.
- To identify potential protein factors involved in the yeast-to-mycelia transition.
- To investigate the role of soluble proteins in C. albicans morphogenesis.
Main Methods:
- Yeast and germ tube formation were induced in carbon-starved cells under various conditions (temperature, carbon source, pH).
- Cell-free S100 fractions were analyzed using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and silver staining.
- Affinity chromatography (polyethylenimine and heparin-agarose) was employed to isolate DNA-binding proteins and other soluble factors.
Main Results:
- Over 400 constitutively synthesized polypeptides were identified in both yeast and germ tube-forming cells.
- No unique polypeptides were exclusively found in either morphology.
- Heparin-agarose chromatography revealed novel, low-abundance polypeptides (130-200 kDa) preferentially synthesized during germ tube formation.
Conclusions:
- The study suggests that key protein factors regulating early germ tube formation in C. albicans are present in low abundance.
- A distinct, minor group of soluble proteins may be differentially synthesized and involved in C. albicans morphogenesis.
- Further research is needed to characterize these low-abundance proteins and their specific roles.