Generating cell surface diversity inCandida albicansand other fungal pathogens

Abstract

The fungal cell surface contributes to pathogenesis by mediating interactions with host cells and eliciting host immune responses. This review focuses on the cell wall proteome of the major fungal pathogen Candida albicans and discusses how diversity at the cell surface can be introduced by altering the expression and structure of cell wall proteins. Remodelling the cell wall architecture is critical to maintain cellular integrity in response to different environments and stresses including challenge with antifungal drugs. In addition, the dynamic nature of the cell surface alters the physical properties of the fungal interface with host cells and thereby influences adhesion to the host and recognition by components of the host's immune system. Examples of the role of cell surface diversity in the pathogenesis of a number of microorganisms are described.

Fungal Morphogenesis

“…Therefore, morphological and physiological plasticity allows fungi to rapidly adapt to changing extracellular conditions. Species-specific signaling and morphological features appear to be a direct result of fungal attempts to survive as new microenvironments, and their particular cell stresses, were encountered (Hogan and Klein 1994;Newman et al 1995;Batanghari et al 1998;Sebghati et al 2000;Gow et al 2002;Brandhorst et al 2004;Rappleye et al 2004Rappleye et al , 2007Gantner et al 2005;Nemecek et al 2006;Gauthier and Klein 2008;Nather and Munro 2008;Mora-Montes et al 2011;. The concerted action of morphotype and physiological changes in the context of a particular environment are therefore critical for successful fungal adaptation (Butler et al 2009;O'Connor et al 2010).…”

The Cell Wall of the Human Pathogen Candida glabrata : Differential Incorporation of Novel Adhesin-Like Wall Proteins

“…However, the proteomic analysis on ATCC 90876 log-phase cells did not result in identification of Strain-and growth phase-dependent in vitro adhesion capacity. Frequently, large allelic variations occur in the structure and expression of fungal cell wall adhesin genes (43,63,64). Independent isolates may express and incorporate different proteins, with direct consequences for cell surface properties, such as the adhesion capacity.…”

“…Several signaling pathways have been identified that regulate the expression of cell wall proteins in response to nutrient limitation, stress, or other signals. Additional adaptive properties are provided through an enormous genetic variability of cell wall proteins, e.g., through subtelomeric epigenetic switching or recombination of intragenic tandem repeats within cell wall genes (17,43,63,64). The effect of variability of tandem repeats on functional diversity of cell surface proteins has been shown for the Flo family in S. cerevisiae, members of which mediate yeast flocculation and adherence to abiotic surfaces, such as agar and plastic (23,61,64).…”

The role of pattern recognition receptors in the innate recognition ofCandida albicans

“…Glucans are key fungal PAMPs. 18,19,118 A recent study revealed that glucans from C. albicans hyphae are different from those from yeast cells. Hyphal glucan induces robust immune responses in human PBMCs and macrophages via a Dectin-1-dependent mechanism.…”

“…Although the basic components of the cell wall are similar, the precise structure and chemical properties are different in different forms of C. albicans, which may facilitate host immune system to recognize different cell forms. 18,19 Host innate immunity to C. albicans critically requires pattern recognition receptors (PRRs). PRRs is fundamental in discriminating self from non-self via recognizing vital conserved chemical signatures of pathogens, called pathogen-associated molecular patterns (PAMPs).…”