Complications in cell-surface labelling by biotinylation of Candida albicans due to avidin conjugate binding to cell-wall proteins.


Journal Article

Initial contact between the opportunistic fungal pathogen Candida albicans and host tissue occurs at the cell surface. Biotin derivatives have been used to label the cell-surface proteins of yeasts, with labelled proteins subsequently detected by avidin-reporter conjugates. Previous work has indicated that avidin can bind to C. albicans proteins in the absence of biotin, suggesting a possible host-cell-recognition mechanism by fungal cell-surface proteins. To investigate this mechanism, Western blots of proteins extracted from biotinylated and mock-treated cells were probed with avidin or modified-avidin reagents. Each avidin reagent bound to cell-wall proteins extracted from non-biotinylated cells. Binding did not appear to be due to the lectin-like activity of the cell-wall proteins of C. albicans or to the presence of biotin in the sample itself. Binding was inhibited by added biotin, by the chaotrope KSCN and by NaCl in a concentration-dependent manner, although inhibition varied among the avidin conjugates tested. Thus, the non-specific binding of avidin to the cell-wall proteins of C. albicans appears to involve hydrophobic and electrostatic interactions, depending on the particular avidin species. These observations demonstrate potential pitfalls in the use of avidin-biotin complexes to identify cell-surface molecules and could provide insights into protein-protein interactions at the C. albicans cell wall.

Full Text

Cited Authors

  • Masuoka, J; Guthrie, LN; Hazen, KC

Published Date

  • April 2002

Published In

Volume / Issue

  • 148 / Pt 4

Start / End Page

  • 1073 - 1079

PubMed ID

  • 11932452

Pubmed Central ID

  • 11932452

Electronic International Standard Serial Number (EISSN)

  • 1465-2080

International Standard Serial Number (ISSN)

  • 1350-0872

Digital Object Identifier (DOI)

  • 10.1099/00221287-148-4-1073


  • eng