Publication
Title
First report of urease activity in the novel systemic fungal pathogen Emergomyces africanus : a comparison with the neurotrope Cryptococcus neoformans
Author
Abstract
Cryptococcus neoformans is an opportunistic pathogen responsible for the AIDS-defining illness, cryptococcal meningitis. During the disease process, entry of cryptococcal cells into the brain is facilitated by virulence factors that include urease enzyme activity. A novel species of an Emmonsia-like fungus, recently named Emergomyces africanus, was identified as a cause of disseminated mycosis in HIV-infected persons in South Africa. However, in contrast to C. neoformans, the enzymes produced by this fungus, some of which may be involved in pathogenesis, have not been described. Using a clinical isolate of C. neoformans as a reference, the study aim was to confirm, characterise and quantify urease activity in E. africanus clinical isolates. Urease activity was tested using Christensen's urea agar, after which the presence of a urease gene in the genome of E. africanus was confirmed using gene sequence analysis. Subsequent evaluation of colorimetric enzyme assay data, using Michaelis-Menten enzyme kinetics, revealed similarities between the substrate affinity of the urease enzyme produced by E. africanus (K-m ca. 26.0 mM) and that of C. neoformans (K-m ca. 20.6 mM). However, the addition of 2.5 g/l urea to the culture medium stimulated urease activity of E. africanus, whereas nutrient limitation notably increased cryptococcal urease activity.
Language
English
Source (journal)
FEMS yeast research / Federation of European Microbiological Societies. - Amsterdam
Publication
Amsterdam : 2017
ISSN
1567-1356 [print]
1567-1364 [online]
DOI
10.1093/FEMSYR/FOX069
Volume/pages
17 :7 (2017) , 10 p.
Article Reference
fox069
ISI
000416721200009
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
Faculty/Department
Research group
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identifier
Creation 21.12.2017
Last edited 09.10.2023
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