Identification
of cell surface determinants in Candida albicans.
Constantin Urban (1), Kai Sohn (1), Friedrich Lottspeich (2), Michael Schweikert
(3), Herwig Brunner (1), Steffen Rupp (1)
(1) IGB, Fraunhofer, Nobelstrasse 12, Stuttgart, 70569, Germany
(cur@igb.fhg.de); (2) Max Planck Institute of Biochemistry, Am Klopferspitz,
Martinsried 82152, Germany; (3) University of Stuttgart, Department of Zoology,
Biological Institute, Am Pfaffenwaldring, Stuttgart 70550, Germany
The cell wall
and surface of Candida albicans, the predominant opportunistic fungal pathogen
in humans, is a highly dynamic organelle having essential functions in
adhesion, virulence and dimorphism. To identify cell surface proteins and to
determine differential incorporation during the dimorphic switch, we have
established a method to specifically biotinylate these proteins using an
activated biotin derivative that is not able to penetrate membranes.
Biotinylated proteins were subsequently purified by neutravidin affinity
chromatography. We have identified 16 cell surface localized proteins in
blastospores as well as in hyphae. Among them were cell wall mannoproteins,
heat shock proteins and glycolytic enzymes. Thiol-specific antioxidant like
protein 1 (Tsa1p) was found to be localized on hyphal cell surfaces but not on
those of blastospores. Astoundingly, Tsa1p translocated from the nucleus in
blastospores to the cytoplasm and cell surface in hyphal cells. Thus, Tsa1p is
differentially localized rather than being differentially expressed depending
on morphology and growth conditions. This kind of differential localization of
proteins has not been reported in C. albicans yet.