Binding of Candida albicans to immobilized amino acids and bovine serum albumin

Abstract

In this study, we examined the binding of Candida albicans synchronized yeast-phase cells to plastic, immobilized amino acids and bovine serum albumin (BSA) and quantified the binding by using an XTT tetrazolium salt assay and absorbance determination. Our results show that C. albicans binds efficiently and specifically to several nonpolar aliphatic amino acids and positively charged amino acids and to BSA immobilized on tissue culture plastic but not to polar uncharged, negatively charged, or aromatic amino acids. Adhesion of yeasts to immobilized amino acids was not affected by preincubation of cells with BSA, whereas binding to immobilized BSA was affected by preincubation of yeasts with alanine, proline, and leucine but not by arginine or lysine. The ability to distinguish the chirality of these amino acids was also examined by using both the D and L amino acid configurations, and the results show that C. albicans yeasts recognize only the L configuration of these amino acids. The observations that C. albicans specifically binds to certain amino acids indicate that these amino acids may prove useful tools for studying the binding interactions of C. albicans yeasts with host proteins such as components of the extracellular matrix.

FIG. 1

(A) Binding of yeasts to plastic, BSA, or gelatin quantified by light microscopy (see Materials and Methods). The bars represent the means (n = 4) ± standard deviations from a typical experiment. (B) Quantification of yeasts bound to plastic, BSA, or gelatin by the XTT tetrazolium salt procedure. XTT formazan was measured after 3.5 h of incubation, and the bars represent the means ± standard deviations (n = 21).

FIG. 2

Binding of yeast cells to immobilized BSA. (A) Binding of yeast cells to BSA (BSA), effects of preincubation with BSA on binding of yeast cells to immobilized BSA (BSA/BSA) and following washout of free BSA [BSA(wash)/BSA], and effects of preincubation with gelatin on the binding of yeast cells to immobilized BSA (PreGel-BSA). (B) Effects of preincubation of yeast cells with 0.001 to 10 mg of BSA per ml on binding of yeast cells to immobilized BSA (BSA pretreatment followed by removal of free BSA in solution or BSA treatment only). Data points represent the means ± standard deviation (n = 20) of yeast cell binding from a typical experiment.

FIG. 3

Measurements of the binding of yeast cells to l and d configurations of immobilized alanine (ALA), arginine (ARG), leucine (LEU), lysine (LYS), and proline (PRO). The bars represent the means ± standard deviations (n = 20) of yeast cell binding from a typical experiment.

FIG. 4

Effects of preincubation of yeast cells with BSA on the binding of yeast cells to immobilized alanine (ALA), arginine (ARG), leucine (LEU), lysine (LYS), or proline (PRO). Data points represent the means ± standard deviations (n = 20) of yeast cell binding from a typical experiment.