Isolation of a Candida albicans DNA sequence conferring adhesion and aggregation on Saccharomyces cerevisiae

Abstract

Candida albicans is an opportunistic pathogen which may give rise to superficial and systemic infections. In the present study, C. albicans adhesion was studied by expression of C. albicans DNA sequences encoding adhesion functions in a nonadherent strain of Saccharomyces cerevisiae. Adherent transformant cells of S. cerevisiae harbouring a C. albicans genomic library cloned in a yeast-Escherichia coli shuttle vector were selected by using tissue culture-treated polystyrene as the attachment substratum. One transformant exhibited enhanced adhesion to treated and untreated polystyrene as well as autoaggregation, unlike control cells bearing the vector alone. Analysis of this clone revealed an insert of ca. 4.5 kb from C. albicans. Curing of the plasmid resulted in loss of adhesion and autoaggregation properties. A subclone bearing a reduced insert of 3.3 kb retained the ability to autoaggregate, to bind to treated and untreated polystyrene, and to adhere to buccal epithelial cells, unlike appropriate controls. Further subcloning of the insert to 2.7- and 1.9-kb fragments resulted in incremental decreases in adhesion and autoaggregation, whereas smaller fragments did not confer these properties. Hybridization of the 2.7-kb segment with C. albicans and S. cerevisiae DNA confirmed its origin as a single-copy sequence in the C. albicans genome as well as the absence of a homologous sequence in the genome of S. cerevisiae. The data suggest that the adhesion and aggregation phenomena of the transformant cells are related to expression of a C. albicans surface antigen encoded by the cloned DNA fragment.

Increase in virulence ofSporothrix brasiliensisover five years in a patient with chronic disseminated sporotrichosis

“…18,19 Virulence determinants include factors required for recognition and invasion of the host and for protection against host defense systems. 20 Since the cell wall is involved in these processes, it protects the fungal cell from external injury, regulates adherence of host cells to components of the cell-wall components [21][22][23] and, therefore, mediates immune responses. [24][25][26][27] Therefore, any changes in the cell-wall structure as well as in its composition may affect fungal virulence.…”

Cloning and expression of a gene encoding an integrin-like protein in Candida albicans.

“…A full or partial MIDAS motif is present in all members of the I domain superfamily (15,33 (40). Another putative candidal adhesin is encoded by a 3.3-kbp genomic DNA fragment and enables transformed S. cerevisiae to adhere to polystyrene or buccal epithelial cells (41). However, its restriction map differs markedly from that of aINT1, and the nucleotide sequence has not been published.…”

The Candida albicans HYR1 gene, which is activated in response to hyphal development, belongs to a gene family encoding yeast cell wall proteins

“…Similarly, the aberrant expression of a structural protein (when the ADH1-HYR1 fusion was used) was unlikely to force hyphal development under conditions which favor the growth of C. albicans yeast cells. Finally, the fact that the ADH1-HYR1 fusion did not affect the self-agglutination of C. albicans or S. cerevisiae yeast cells suggests that Hyr1p is distinct from a previously isolated C. albicans genomic fragment which can promote the self-aggregation of S. cerevisiae cells (2).…”