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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Cell Wall Biology and Utilization Research » Research » Publications at this Location » Publication #302908
Title: Novel entries in a fungal biofilm matrix encyclopedia

Author
item ZARNOWSKI, ROBERT - University Of Wisconsin
item WESTLER, WILLIAM - University Of Wisconsin
item LACMBOUH, GHISLAIN - University Of Wisconsin
item Marita, Jane
item BOTHE, JAMESON - University Of Wisconsin
item BERNHARDT, J - Ernst Moritz Arndt University Of Greifswald
item SAHRAOUI, ANNISA - Université Du Littoral Côte D’Opale, Unité De Chimie Environnementale At Interactions Sur Le Vivant
item FONTAINE, JOEL - Université Du Littoral Côte D’Opale, Unité De Chimie Environnementale At Interactions Sur Le Vivant
item SANCHEZ, HIRAM - University Of Wisconsin
item Hatfield, Ronald
item NTAMBI, JAMES - University Of Wisconsin
item NETT, JENIEL - University Of Wisconsin
item MITCHELL, AARON - Carnegie Mellon University
item ANDES, DAVID - University Of Wisconsin

Submitted to: mBio
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2014
Publication Date: 8/5/2014
Citation: Zarnowski, R., Westler, W.M., Lacmbouh, G.A., Marita, J.M., Bothe, J., Bernhardt, J., Sahraoui, A., Fontaine, J., Sanchez, H., Hatfield, R.D., Ntambi, J.M., Nett, J.E., Mitchell, A.P., Andes, D.R. 2014. Novel entries in a fungal biofilm matrix encyclopedia. mBio. 5(4):e01333-14.

Interpretive Summary: Fungal infections are particularly difficult to control when occurring in humans. Part of the reason for this resistance to treatment is how the fungal organism becomes established and grows in humans. In the case of Candida albicans, a common fungal pathogen, the fungus grows and develops a complex mixture of carbohydrates, proteins, and fats as a support and protection film called a “biofilm”. The biofilm is believed to be a major reason this fungus is so hard to treat when it infects humans. Little is known about the detailed makeup of these biofilms and how they may contribute to resistance to treatments. The work described in this paper provides a detailed characterization of what makes up the biofilm and identifies reasons that lead to resistance to treatment. The biofilm examined here was made up of 55% protein, 25% carbohydrate, 15% lipid, and 5% nucleic acid by weight. Interaction of biofilm components resulted in binding of the commonly used antifungal, fluconazole. This is similar to a role in drug binding as identified in previous studies. Individual biofilm components did not show anti-fungal binding, also supporting a multi-component biofilm-drug interaction model. In other words, it is the complex nature of the biofilm itself that binds drugs, protecting the main fungus from their anti-fungal properties. The biofilm component analysis provides an important information resource that opens the door to understanding how it works and its role in the fungal life cycle.

Technical Abstract: Virulence of Candida albicans is linked with its ability to form biofilms. Once established, biofilm infections are nearly impossible to eradicate. Biofilm cells live immersed in a self-produced matrix, a blend of extracellular biopolymers, many of which are uncharacterized. In this study, we conducted a comprehensive analysis of the matrix produced by C. albicans, both in vitro and in a clinical niche animal model. The function of matrix components, including the impact on drug resistance, was also explored. We found the matrix to be composed of components from each of the major macromolecular classes (55% protein, 25% carbohydrate, 15% lipid, and 5% nucleic acid by weight). Three main polysaccharides were identified and shown to interact physically and functionally through several lines of evidence. Surprisingly, a previously identified component of functional importance, beta-1,3 glucan, comprised only a small portion of the total matrix carbohydrate. Newly described, more abundant novel polysaccharides included alpha-1,2 branched alpha-1,6 mannans (87%) conjugated to unbranched beta-1,6 glucans (13%). The functional matrix proteomic analysis revealed 458 distinct activities. The matrix lipids consisted of neutral glycerolipids (89.2%), polar glycerolipids (10.4%), and trace amounts of sphingolipids (0.5%). Examination of matrix nucleic acid identified DNA, primarily random non-coding sequences. Many of the in vitro matrix components, including proteins and each of the polysaccharides, were also present in the matrix of a clinically relevant animal biofilm infection model. NMR interaction analysis demonstrated interaction of aggregate matrix to the commonly used antifungal, fluconazole, consistent with a role in drug impedance as identified in previous studies. The NMR pattern suggested cooperative interaction to more than one matrix constituent. NMR study of select, individual matrix components did not show antifungal binding, also supporting a multi-component matrix-drug interaction model. The availability of these comprehensive biochemical matrix analyses provides a unique resource that opens the door to investigations examining the biofilm matrix, a defining trait of this microbial lifestyle.