Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human pathogenic fungus Cryptococcus neoformans secretes a phospholipase enzyme that demonstrates phospholipase B (PLB), lysophospholipase hydrolase and lysophospholipase transacylase activities. This enzyme has been postulated to be a cryptococcal virulence factor. We cloned a phospholipase-encoding gene (PLB1) from C. neoformans and constructed plb1 mutants using targeted gene disruption. All three enzyme activities were markedly reduced in the mutants compared with the wild-type parent. The plb1 strains did not have any defects in the known cryptococcal virulence phenotypes of growth at 37 degrees C, capsule formation, laccase activity and urease activity. The plb1 strains were reconstituted using the wild-type locus and this resulted in restoration of all extracellular PLB activities. In vivo testing demonstrated that the plb1 strain was significantly less virulent than the control strains in both the mouse inhalational model and the rabbit meningitis model. We also found that the plb1 strain exhibited a growth defect in a macrophage-like cell line. These data demonstrate that secretory phospholipase is a virulence factor for C. neoformans.
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PMID:Extracellular phospholipase activity is a virulence factor for Cryptococcus neoformans. 1112 98

Disseminated cryptococcosis begins with infection of the lungs via inhalation. This is followed by escape from the lungs and entry into the bloodstream allowing dissemination to the brain and central nervous system. We discuss the steps involved in dissemination and the host and microbial factors that influence each step. For the host, containment in the lung is accomplished with a combination of cell-mediated and antibody responses. Dissemination occurs when these systems fail and/or when phagocytic cells that fail to kill the yeast instead act as a niche for replication. One of the main microbial factors affecting dissemination is the polysaccharide capsule, a major virulence factor that promotes dissemination at every step. Secreted enzymes are important, including laccase and phospholipase B, which promote escape from the lungs, and urease, which contributes to crossing the blood-brain barrier. Lastly, a number of regulatory factors contribute, especially to growth of Cryptococcus neoformans in the brain.
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PMID:New insights on the pathogenesis of invasive Cryptococcus neoformans infection. 1799 81

Different phenotypic characteristics associated with virulence of the Cryptococcus neoformans species complex have shown an important role in their pathogenicity. In this study we have determined the role of phenotypically and genotypically factors of some virulence factors from clinical isolates in the two species of the complex; 35 C. neoformans and 19 Cryptococcus gattii. Growth at 37 degrees C, macroscopic and microscopic morphology, switching phenomenon, activity of 23 extracellular enzymes, variability of the colonies in agar with phloxin B; phospholipase B gene, and the mating type were determined by PCR; the molecular pattern was determined by URA5 RFLP. All isolates grew at 37 degrees C, the capsular size was greater in C. gattii (1.87 microm -/+1.47 microm) than in C. neoformans (0.83 microm -/+0.15 microm). Switching was observed mainly in isolates of C. gattii. All isolates expressed the enzyme urease, a lower activity of the proteases (Pz= 0.54), but a higher activity of the phospholipase (Pz=0.43) and phenoloxidase (Pz=0.003) was determined for C. gattii.
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PMID:[In vitro determination of virulence factors activity associated with several Cryptococcus neoformans clinical isolates]. 1878 82