| Chitinases are essential for sexual development but not vegetative growth in Cryptococcus neoformans. | |
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MedLine Citation:
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PMID: 19734369 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Cryptococcus neoformans is an opportunistic pathogen that mainly infects immunocompromised individuals. The fungal cell wall of C. neoformans is an excellent target for antifungal therapies since it is an essential organelle that provides cell structure and integrity. Importantly, it is needed for localization or attachment of known virulence factors, including melanin, phospholipase, and the polysaccharide capsule. The polysaccharide fraction of the cryptococcal cell wall is a complex structure composed of chitin, chitosan, and glucans. Chitin is an indispensable component of many fungal cell walls that contributes significantly to cell wall strength and integrity. Fungal cell walls are very dynamic, constantly changing during cell division and morphogenesis. Hydrolytic enzymes, such as chitinases, have been implicated in the maintenance of cell wall plasticity and separation of the mother and daughter cells at the bud neck during vegetative growth in yeast. In C. neoformans we identified four predicted endochitinases, CHI2, CHI21, CHI22, and CHI4, and a predicted exochitinase, hexosaminidase, HEX1. Enzymatic analysis indicated that Chi2, Chi22, and Hex1 actively degraded chitinoligomeric substrates. Chi2 and Hex1 activity was associated mostly with the cellular fraction, and Chi22 activity was more prominent in the supernatant. The enzymatic activity of Hex1 increased when grown in media containing only N-acetylglucosamine as a carbon source, suggesting that its activity may be inducible by chitin degradation products. Using a quadruple endochitinase deletion strain, we determined that the endochitinases do not affect the growth or morphology of C. neoformans during asexual reproduction. However, mating assays indicated that Chi2, Chi21, and Chi4 are each involved in sexual reproduction. In summary, the endochitinases were found to be dispensable for routine vegetative growth but not sexual reproduction. |
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Authors:
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Lorina G Baker; Charles A Specht; Jennifer K Lodge |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2009-09-04 |
Journal Detail:
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Title: Eukaryotic cell Volume: 8 ISSN: 1535-9786 ISO Abbreviation: Eukaryotic Cell Publication Date: 2009 Nov |
Date Detail:
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Created Date: 2009-11-02 Completed Date: 2010-01-14 Revised Date: 2010-12-03 |
Medline Journal Info:
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Nlm Unique ID: 101130731 Medline TA: Eukaryot Cell Country: United States |
Other Details:
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Languages: eng Pagination: 1692-705 Citation Subset: IM |
Affiliation:
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Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8230, St. Louis, MO 63104, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Chitinase
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genetics,
metabolism* Cryptococcus neoformans / enzymology*, genetics, growth & development* Fungal Proteins / genetics, metabolism* Gene Expression Regulation, Fungal Reproduction, Asexual |
| Grant Support | |
ID/Acronym/Agency:
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R01 AI072195-05/AI/NIAID NIH HHS; R01AI072185/AI/NIAID NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Fungal Proteins; EC 3.2.1.14/Chitinase |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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