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Cryptococcus gattii urease as a virulence factor and the relevance of enzymatic activity in cryptococcosis pathogenesis
Author(s) -
Feder Vanessa,
Kmetzsch Lívia,
Staats Charley Christian,
VidalFigueiredo Natalia,
LigabueBraun Rodrigo,
Carlini Célia Regina,
Vainstein Marilene Henning
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13229
Subject(s) - urease , cryptococcosis , microbiology and biotechnology , virulence factor , cryptococcus gattii , virulence , cryptococcus neoformans , biology , bacteria , pathogenesis , enzyme , biochemistry , gene , immunology , genetics
Ureases ( EC 3.5.1.5 ) are Ni 2+ ‐dependent metalloenzymes produced by plants, fungi and bacteria that hydrolyze urea to produce ammonia and CO 2 . The insertion of nickel atoms into the apo‐urease is better characterized in bacteria, and requires at least three accessory proteins: UreD, UreF, and UreG. Our group has demonstrated that ureases possess ureolytic activity‐independent biological properties that could contribute to the pathogenicity of urease‐producing microorganisms. The presence of urease in pathogenic bacteria strongly correlates with pathogenesis in some human diseases. Some medically important fungi also produce urease, including Cryptococcus neoformans and Cryptococcus gattii . C. gattii is an etiological agent of cryptococcosis, most often affecting immunocompetent individuals. The cryptococcal urease might play an important role in pathogenesis. It has been proposed that ammonia produced via urease action might damage the host endothelium, which would enable yeast transmigration towards the central nervous system. To analyze the role of urease as a virulence factor in C. gattii , we constructed knockout mutants for the structural urease‐coding gene URE1 and for genes that code the accessory proteins Ure4 and Ure6. All knockout mutants showed reduced multiplication within macrophages. In intranasally infected mice, the ure1 Δ (lacking urease protein) and ure4 Δ (enzymatically inactive apo‐urease) mutants caused reduced blood burdens and a delayed time of death, whereas the ure6 Δ (enzymatically inactive apo‐urease) mutant showed time and dose dependency with regard to fungal burden. Our results suggest that C. gattii urease plays an important role in virulence, in part possibly through enzyme activity‐independent mechanism(s).