Clonación y caracterización de una hidrofobina de clase II (CaHPB) de Candida albicans

Résumé

In this work, we have cloned and characterized a class II hydrophobin-like molecule in the opportunistic pathogenic fungus Candida albicans, which exhibits all the characteristics previously described for this type of secretory proteins in other fungal species. Hydrophobins are a small secreted fungal proteins that self-assemble at hydrophilic/hydrophobic interfaces into amphipathic films thereby changing the nature of surfaces (i.e., hydrophobic surfaces become hydrophilic, while hydrophilic surfaces become hydrophobic) and are among the most surface-active biosurfactants known. This attribute can be used to introduce hydrophobic foci on the surface of hydrophilic supports where hydrophobins are attached by covalent binding in response to the environment. Hydrophobins are characterized by the presence of eight conserved cysteine residues that from four disulphide bridges and by a typical hidropathy pattern. Hydrophobins have been classified into two classes, class I and class II hydrophobins. Apart from eight conserved cysteine residues, the amino acid sequences between and within both classes have diverged considerably, and this is reflected in the biophysical properties of these proteins. For instance, assemblages of class I hydrophobins are highly insoluble and only can be dissolved by treatment with formic acid or trifluoroacetic acid, while those of class II hydrophobins only can be dissolved by SDS or ethanol. The properties of hydrophobins make them interesting candidates for use in a wide range of medical and technical applications. Each application has its own requirements, which may be met by using specific natural variants of hydropnobins or by modifying hydrophobins chemically or genetically. Applications also require high production systems for hydrophobins. In this respect, filamentous fungi that naturally secrete hydrophobins into the medium seem to be the hosts of choice. They have been shown to be important in many morphogenetic processes, including sporulation, fruit body development, and infection structure formation. The characterization for the first time of a molecule of this nature in C. albicans may open new therapeutic and diagnostic approaches for the management of candidiasis, since hydrophobins most likely may be related with virulence (allowing the fungal cells to interact better with host tissues during infection) and these kind of fungal moieties are not synthesized by animal cells.