Cell surface adhesins mediate the first interactions of fungi with mammalian hosts, so adhesin-mediated binding is a prelude to differentiation, colonization, biofilm formation and pathogenic invasion. These events in turn lead to complications of morbidity and mortality, especially common in immunocompromised and chronic disease patients. The C. albicans Als adhesins are implicated in pathogenesis and biofilm formation. They bind to mammalian tissues, cause fungal cell aggregation, and also co-aggregate with other microbial pathogens to mediate polymicrobial infections. Als adhesins are also important in formation of persistent and drug-resistant biofilms in tissues and on indwelling devices. Our long-term goal is to understand the roles for cell adhesion proteins in fungal life cycles and pathogenesis. The central hypothesis of this proposal is that amyloid-forming sequences are a feature of biofilm-forming adhesins, and these sequences potentiate adhesion, fungal aggregation and host invasion. This hypothesis is based on our findings that Als5p causes adherence with amyloid-like features, that the purified Als5p can form authentic amyloids, and that bioinformatic analyses reveal amyloid-forming sequences in many biofilm-associated microbial adhesins.
Three specific aims will test the amyloid/ biofilm hypothesis: (1) To determine the role of specific sequences in amyloid formation and microbial adherence, we will test the working hypothesis that the amyloid-forming sequences are essential for Als-mediated cellular aggregation. (2) We will test the hypothesis that these amyloid-forming sequences in Als proteins are essential for Als-initiated biofilm formation. (3) In Als proteins, glycosylated tandem repeats follow the amyloid-forming sequences, and these repeats greatly increase adhesion activity. We will therefore test the hypothesis that the peptide sequences and glycosylation patterns in the Als repeats modulate amyloid formation to promote cellular aggregation and biofilm formation. The proposed work is innovative in its conjunction of two important concepts: amyloid-like protein interactions and adherence of pathogens leading to biofilm formation. We are also the first group to work on structure and function of Thr-rich repeat sequences in pathogenic and other fungal adhesins. Completion of these aims will lead to better defined models for the initial events in biofilm formation, and will discover whether amyloid-forming sequences are essential for biofilm adherence in fungi. If the hypothesis is supported, the results will establish connections between searches for anti-biofilm and anti-amyloid therapeutic agents.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Enhancement Award (SC1)
Project #
5SC1GM083756-03
Application #
7816985
Study Section
Special Emphasis Panel (ZGM1-MBRS-8 (MV))
Program Officer
Anderson, James J
Project Start
2008-06-20
Project End
2012-04-30
Budget Start
2010-05-01
Budget End
2011-04-30
Support Year
3
Fiscal Year
2010
Total Cost
$353,250
Indirect Cost
Name
Brooklyn College
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
620127691
City
New York
State
NY
Country
United States
Zip Code
11210
Garcia-Sherman, Melissa C; Lysak, Nataliya; Filonenko, Alexandra et al. (2014) Peptide detection of fungal functional amyloids in infected tissue. PLoS One 9:e86067
Lipke, Peter N; Ramsook, Caleen; Garcia-Sherman, Melissa C et al. (2014) Between Amyloids and Aggregation Lies a Connection with Strength and Adhesion. New J Sci 2014:815102
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El-Kirat-Chatel, Sofiane; Beaussart, Audrey; Alsteens, David et al. (2013) Nanoscale analysis of caspofungin-induced cell surface remodelling in Candida albicans. Nanoscale 5:1105-15
Garcia, Mc; Lipke, Pn; Klotz, Sa (2013) Pathogenic microbial amyloids: Their function and the host response. OA Microbiol 1:
Bois, Michael; Singh, Sean; Samlalsingh, Alyssa et al. (2013) Does Candida albicans Als5p amyloid play a role in commensalism in Caenorhabditis elegans? Eukaryot Cell 12:703-11
Beaussart, Audrey; Alsteens, David; El-Kirat-Chatel, Sofiane et al. (2012) Single-molecule imaging and functional analysis of Als adhesins and mannans during Candida albicans morphogenesis. ACS Nano 6:10950-64
Heinisch, Jurgen J; Lipke, Peter N; Beaussart, Audrey et al. (2012) Atomic force microscopy - looking at mechanosensors on the cell surface. J Cell Sci 125:4189-95
Gilchrist, Kevin B; Garcia, Melissa C; Sobonya, Richard et al. (2012) New features of invasive candidiasis in humans: amyloid formation by fungi and deposition of serum amyloid P component by the host. J Infect Dis 206:1473-8
Lipke, Peter N; Garcia, Melissa C; Alsteens, David et al. (2012) Strengthening relationships: amyloids create adhesion nanodomains in yeasts. Trends Microbiol 20:59-65

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