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Title:Peering into Candida albicans pir protein function
Author(s):Kim, Jisoo
Advisor(s):Hoyer, Lois L.
Contributor(s):Lau, Gee; Miller, Michael J.; Witola, William H.
Department / Program:Pathobiology
Discipline:VMS - Pathobiology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:The fungal cell wall, which primarily is comprised of protein and polymeric carbohydrate, maintains cell structure and protects the fungal cell from the environment. Cell wall structure is an avid field of study because the cell wall is an important antifungal drug target. Pir proteins (proteins with internal repeats), which are linked to β-1,3-glucan in the cell wall, were characterized initially in Saccharomyces cerevisiae, then detected in other fungal species. Despite extensive work in S. cerevisiae, a true null mutant that lacked each of the 5 PIR genes was never constructed. Parallel studies in C. albicans indicated the presence of two PIR genes: PIR1 and PIR32. Literature reports suggested allelic variation in the C. albicans PIR genes that was not described for S. cerevisiae, and that deletion of C. albicans PIR1 was a lethal event. The goal of the work presented here was to further explore C. albicans PIR genes and to construct the first true null Δpir/Δpir mutant. PIR1 had considerably more allelic variability than PIR32. Differences were due to numbers of copies of a repeated motif that encodes the amino acid sequence involved in linking Pir proteins to the cell wall. Despite dire predictions from the literature, the Δpir1/Δpir1 Δpir32/Δpir32 strain was viable and only mildly affected when grown in the presence of compounds that interfere with cell wall biosynthesis. Lack of a pronounced phenotype in the null mutant suggested that C. albicans may have compensatory mechanisms that stabilize cell wall structure. BLAST searching revealed a family of nine proteins that share a conserved Pir sequence motif (minimally DGQ) that is involved in linking proteins to the fungal cell wall. Alignment of the nine new proteins revealed the presence of another conserved sequence motif (QFQFD) that is present in all known Pir proteins. Future studies will focus on investigating the role of the newly recognized motif in maintaining fungal cell wall architecture.
Issue Date:2017-11-21
Rights Information:Copyright 2017 Jisoo Kim
Date Available in IDEALS:2018-03-13
Date Deposited:2017-12

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