Chitin synthesis and fungal pathogenesis. Curr Opin Microbiol

Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK.
Current opinion in microbiology (Impact Factor: 5.9). 08/2010; 13(4):416-23. DOI: 10.1016/j.mib.2010.05.002
Source: PubMed


Chitin is an essential part of the carbohydrate skeleton of the fungal cell wall and is a molecule that is not represented in humans and other vertebrates. Complex regulatory mechanisms enable chitin to be positioned at specific sites throughout the cell cycle to maintain the overall strength of the wall and enable rapid, life-saving modifications to be made under cell wall stress conditions. Chitin has also recently emerged as a significant player in the activation and attenuation of immune responses to fungi and other chitin-containing parasites. This review summarises latest advances in the analysis of chitin synthesis regulation in the context of fungal pathogenesis.

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Available from: Megan Denise Lenardon, Aug 13, 2015
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    • "Importantly, chitin is not found in human cells and therefore represents an attractive target for antifungal therapy. In Candida albicans, the most common serious fungal pathogen of humans, chitin is synthesized by a family of four isoenzymes which fall into three different classes of chitin synthase enzymes, Chs1 (class II), Chs3 (class IV), Chs2 and Chs8 (class I) (reviewed in Lenardon et al. (2010b)). Together, these enzymes deposit chitin at sites of growth, which includes the polarized tips of buds and hyphae, and sites of septation. "
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    ABSTRACT: Candida albicans has four chitin synthases from three different enzyme classes which deposit chitin in the cell wall, including at the polarized tips of growing buds and hyphae, and sites of septation. The two class I enzymes, Chs2 and Chs8, are responsible for most of the measurable chitin synthase activity in vitro, but their precise biological functions in vivo remain obscure. In this work, detailed phenotypic analyses of a chs2Δchs8Δ mutant have shown that C. albicans class I chitin synthases promote cell integrity during early polarized growth in yeast and hyphal cells. This was supported by live cell imaging of YFP-tagged versions of the class I chitin synthases which revealed that Chs2-YFP was localized at sites of polarized growth. Furthermore, a unique and dynamic pattern of localization of the class I enzymes at septa of yeast and hyphae was revealed. Phosphorylation of Chs2 on the serine at position 222 was shown to regulate the amount of Chs2 that is localized to sites of polarized growth and septation. Independently from this post-translational modification, specific cell wall stresses were also shown to regulate the amount of Chs2 that localizes to specific sites in cells, and this was linked to the ability of the class I enzymes to reinforce cell wall integrity during early polarized growth in the presence of these stresses. Copyright © 2015. Published by Elsevier Inc.
    Fungal Genetics and Biology 08/2015; 82. DOI:10.1016/j.fgb.2015.08.001 · 2.59 Impact Factor
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    • "The ability of plants to recognize various PAMPs enables plants to quickly defend against fungal, bacterial, and insect invaders. One of the most common PAMPs is chitin, a fungal cell wall constituent [10]. Chitin is comprised of polymers of N-acetylglucosamine (GlcNAc) residues linked together through a ␤1–4 glycosidic 0927-7765/© 2014 Elsevier B.V. All rights reserved. "
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    ABSTRACT: The biomaterial class of chitooligosaccharides (chitin), commonly found in insects and fungi, is one of the most abundant on earth. Substantial evidence implicates chitin in mediating a diverse array of plant cellular signaling events, including the induction of plant defense mechanisms against invading pests. However, these recognition and mediation mechanisms, including the binding kinetics between chitin and their plant recognition receptors, are not fully understood. Therefore, the creation of a platform capable of both interfacing with chitin and plant cell receptors, and monitoring their interactions, would significantly advance our understanding of this plant defense elicitor. Recently, a label-free, highly sensitive biosensor platform, based on Whispering Gallery Mode optical microresonators, has been developed to study such biomolecular interactions. Here, we demonstrate how this unique platform can be interfaced with chitin using simple carbohydrate chemistry. The surface chemistry is demonstrated using X-ray photoelectron spectroscopy, fluorescence microscopy, optical profilometry, ellipsometry, and contact angle measurements. The resulting surface is uniform, with an average surface roughness of 1.25nm, and is active toward chitin recognition elements. Optical loss measurements using standard quantitative cavity analysis techniques demonstrate that the bioconjugated platforms maintain the high performance (Q>10(6)) required to track binding interactions in this system. The platform is able to detect lectin, which binds COs, at 10μg/mL concentration. This biosensor platform's unique capabilities for label-free, high sensitivity biodetection, when properly interfaced with the biomaterials of interest, could provide the basis for a robust analytical technique to probe the binding dynamics of chitin-plant cell receptors.
    Colloids and surfaces B: Biointerfaces 10/2014; 122:241–249. DOI:10.1016/j.colsurfb.2014.06.067 · 4.15 Impact Factor
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    • "For instance, deletion of the α-glucan encoding ags1 or ags2 had no effect on virulence, while mutation of ags3 increased fungal disease [22]. Chitin, a polymer of N-acetylglucosamine that is covalently linked to β-glucan, is encoded by at least seven chitin synthase (chs) genes in A. fumigatus [23]. Deletion of individual chs genes did not alter fungal virulence in mice, though a double chsC/G mutant exhibited decreased growth and virulence [24]. "
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    ABSTRACT: The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall β-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype.
    PLoS ONE 06/2014; 9(6):e100430. DOI:10.1371/journal.pone.0100430 · 3.23 Impact Factor
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